Do you have a Norton product (NAV, NIS) installed?

If so read

http://service1.symantec.com/SUPPORT/sharedtech.nsf/pfdocs/2005113009323013

Still having problems.  Have WinXP SvcPack3.  Did a virus/malware scan that took 6 hours for 37GB, which is indicative of my problems although nothing was found.  Everything is like molasses.  The problem with System Restore is worse now in that for some reason I have no boldfaced dates other than what I can set today.  Not sure where they went. I don't know of a way to set a restore point for, lets say, a week ago when I was not having these problems. ??? And restoring to a few hours ago (which works) does me no good.  Was having trouble signing on to AOL but reinstalled AOL  9.1 and now that is Okay.  Had installed some Vic Man software (Photo Album & Photo Editing software) but uninstalled it.  No noticeable change as far as System Restore lack of restore points or Slowness of system.  Computer is old, should be replaced, but for time being would just like to get back to where it was a week ago when it was operating adequately.  Do constant maintenance with Windows Live OneCare, System Mechanic (Iolo), and Registry Mechanic (Iolo).  Am at somewhat of a stalemate at this point.  Would settle for having restore points of a week ago but do not know how to achieve that or what happened to the ones I had.   Any more suggestions.  Would Dell diagnostics tell me anything?? 

http://support.microsoft.com/default.aspx?scid=kb;en-us;302796

Dell diagnostics would look for hardware problems.  Did you try safe mode to run system restore?  If that fails you could attempt to reinstall system restore.  The fact your system is also running slow may indicate another issue involved.  Open up task manager and see what your cpu and memory usage is running.  How much free drive space do you have?  Have you tried an online scan from another vendor (kaspersky for example) or malwarebytes free or superantispyware free?  

You raise several point...thank you.  For the time being I have just completed another 2.5 hr scan using SuperAntiSpyware software.  This time 68 'threats' were found and eliminated.  Too early to tell if this is helping with the slowness problem. BTW it never ceases to amaze me how two scans by different software applications within the same time period can reveal amazingly different findings.  Also how some 'try us out' scans can be accomplished in under a minute when others take hours.  I really don't trust a lot of these 'Take the bait' software promotions.

The problem is not that I can't use System Restore (whether by Safe Mode which I haven't done yet or by msconfig/launch System Restore) but rather that all the restore points that I had prior to this current problem have ceased to exist and I don't know how to 'create', or should I say 're-create' a restore point that would be before I was having these problems.  Also where do I go to reinstall System Restore?...and would that do any good in getting back to a previous 'good state'.

I have used 85% of my hard drive  (37GB out of 40GB) and I think that may be part of the problem but why did it occur rather suddenly when this has been the condition for quite some time.

I also want to use 'Selective Startup' and disable a lot of the applications that are being enabled at startup.  Many I rarely use can simply wait in the locker room. lol.

Thanks again for your help.

No, it is not possible to create a system restore point corresponding to the state the system was in some time ago. Once the system restore points are gone there is no way for the system to remember or find out what state is was in at an earlier time.

The system restore points are deleted if you turn off system restore, or if you used disk cleanup utility to remove all but the most recent restore point.

In your first post you pointed out that system restore failed. Since it was not the Norton issue that I had suggested as a possibility, most probably one or other system restore point had got corrupted. As they act like links in a chain (each point stores just the changes since the previous one), if one is corrupted all earlier restore points will also fail. Hence they are of no use, hence the advice to delete them by turning off system restore, restarting and turnig it back on.

Malware scanners such as Superantispyware etc. each have their own databases of malware, hence often what one finds another will not. There is also a difference between antivirus and malware/spyware scanners, they tend to look for different things. There are also many rogue programs that offer an on line scan, 'find' malware or virus and then ask you to pay to buy their bogus software to 'remove' it.

But Superantispyware is one of the best genuine products. The fact that it found so many bad items suggests to me that your system was badly infected, which likely is at the root of your problems. You might consider saving all your personal files to CD/DVD or a second hard drive and reinstalling XP, drivers and software. A somewhat lengthy task, but maybe the most practical solution. There are many guides available, if you have not done this before.

If you don't want to go down that route, then it will certainly do no harm to disable unneeded items from the startup list in msconfig (once you have done that to your satisfaction you don't need to stay in selective mode: just check the box at the bottom of the window telling you you are in selective mode. Next time you restart, you will be in normal mode). Also increasing the available disk space, followed by a defrag could help somewhat. Uninstall programs you don't need, move some of your rarely used personal files to CD/DVD (assuming you have a suitable CD or DVD write drive) or to another hard drive (e.g. you could get an external hard drive that plugs in through a USB port) or a USB flash drive. 

BTW I don't think it is such a good idea to use registry cleaners such as the ones you mentioned. They can often do more harm than good, because often registry entries are mistakenly identified as incorrect and offered for deletion, when in fact they are needed. In any case you should never let any registry cleaner delete all the keys it thinks are incorrect without examining each in detail. That requires a proper understanding of the registry.

Thanks for the comprehensive reply.  The computer is working much better now since the SuperAntiSpyware scan and removal of the 'threats'.  Also, per your suggestion, I will probably stop using Registry Mechanic, but continue to use System Mechanic which has been doing a good job.

I regularly(every 3 mos) back up my personal files (some 3.5 GB) onto DVD using a Sony external DVD burner.  I have been doing this for years, not only as a backup for crash protection but also to have files readily available for transfer to a new computer (if and when).  Although for this purpose I have never understood why I should use backup software such as Nero or BackUPMyPc instead of just burning a DVD Data Disc.  For the same reason when I download a new application I usually also download (but not install) a second .exe in a folder that I call 'Program setups Only', which will serve as a sort of library of applications much like a collection of CD discs would do.  I also regularly refresh that folder on a DVD disc to have for future use.  My computer is old, has only 40GB on the hard drive and is probably about ready for recycling into a new computer.

Thanks for the explanation about System Restore.  Obviously I did something to eliminate the old restore points.

Thanks again for all your help.

Your'e welcome.

Glad to read that you do backup your data :-)