Prior to my post I had checked on system restore and it wouldn't let me do anything,I also got this message..Drive C: has only 0 MB of free disk space..to prevent information loss and performance problems  you need to free up some disk space..see Help and support...System restore might be suspended because there isn't enough disk space available..this means System Restore won't be able to undo harmful changes if they occur.

So after I saw that message thats when I went blank..so I don't even know how to turn System Restore off if its on.

There is malware and the event logs are filling up the drive.  You have to go offline by turning off your router.

You have to turn system restore off, turn hibernate off,  allow event log to over write instead of keep until dooms day. 

Run Cleanmgr.exe and remove system files and system restore points and and and and.

Am I supposed to download the Cleanmgr.exe and then follow the instructions ? Sorry I am not a Pro,just a computer user with some knowledge.

I got the system restore turned off for the C drive,so I guess thats good but I got the info from Microsoft info page how to turn off hibernation and I can't get anywhere with that..I click Start,then in the small box type in cmd and hit enter,a black box opens up on the screen and has admin_,so I tried to type in my info and nothing,so I am doing something wrong.

The hibernation info I have goes like this.

1) Press Windows key on keyboard or click start..type cmd in the start box.

2) In the search results list list right click "command prompt" or cmd & then click "run as administrator".

3) When prompted by user account control,click "continue".

4) At the "command prompt" type powercfg.exe/hibernate off,then press "enter".

When I click  start the small box is there,i type in cmd and hit "enter" and a black box pops up on the screen,and it has admin..so I tried typing in my info and shows nothing found.. I haven't seen any Search result list,run as administer or nothing. anyone ..?

Hi @speedstep, Cleanmgr.exe can be trusted to not remove necessary system files?

Hi @moshpit903, Are you able to access Microsoft Security Essentials?  If so, it should let you run a full scan.  Granted it's updated, it should isolate any malicious files.  Full-scan can take an hour or more.

The "1803" update you mention I believe is for Win10.  Microsoft has been coding Win10 updates yy/mo.  So 1803 came out March 2018.

Hopefully your luck gets better instead of having so many computer problems. :Smile:

Upon further review, when I took a photo for your other thread, Microsoft Security Essentials isn't in the Control Panel of Win7 like I thought.  I might've been thinking of XP.  I saw in your other thread that you found its fortress icon.

I'll have to leave it to speedstep, or others with expertise in this area, to help you further.  For one thing, speedstep has programming experience and his computer expertise goes beyond mine.

first off , we have no idea what HDD or SSD is inside your PC.

780 SFF, MT or mini tower case?  there are 3 models of 780 can we know this?

1803 is NOT W7, so we can forget w10

the PC is 7 years old. (not too old) some page in the manual hint at 2009 and XP.

The first step we do on the BENCH is test the RTC coin cell battery for not less than 2.9vdc,

the we boot a linux test disk or USB stick and run full disktests on that old HDD, including full  S.M.A.R.T TEST IN THAT DRIVE. if that passes, we then back up your data, or are you already backed up? 

with that done, we look to see if the recovery partition is missing or empty, if it look kinda ok, files all there

we run that next, called OS Recovery covered in your manual.

the F12 key at power on , also has  hdd tests under Diagnostics, page 17 in the users manual.

what OS this PC runs NOW is unstated.

what OS it came with day one, with recovery disks or recovery partition is unknown.

it is possible that this PC was upgraded from XP new, then Vista , then w7.

if that happened, only this fact tells me how to rebuild what you have now.

if the HDD passes tests

Id next find out what is  using up all the HDD space.

most reviews in this PC show HDD was 250GB , 10 times what is needed for W7.

so what  ever has filled it up, needs to be deleted.  this is very easy using say a

windows 7 PE service boot demo live disk

or same on a USB STICK

or run Ubuntu v16+ and click tryme.   and that demo mode will let you find what has filled up your hdd.

so :
1: bad hdd.

2: malware infected to the max.

takes my 15 minutes work to find that , in hand.

good luck to you.

the recovery is covered here too..... 1st google hit,  (I know from experience on PCs that the method can vary by what OS was installed new, XP:? some methods need the RECOVERY DISK that came with PC new.

if you have that great or us useless after 3 upgrades sure. (buy then OS new and start over.)

https://www.dell.com/community/Desktops-General-Read-Only/Optiplex-780-restore/td-p/3872547

Hi..I finally got around to messing with my 2 computers..first off your post actually helped me fix my 990 MT and now it's setup and runs perfect with the new hard drive..I checked the batteries voltage and it was .47 so dead,popped in a new hot 3.44v battery set time and date and it now works perect,so THANKS A LOT FOR THAT INFO !!!   Now to my 780..it is the DT size..it has 2 slots for memory on the pcb..I did change that battery as well..I was told here that it's quite possible that Malware has gotten to it..I have McAfee 2019 with all security features on it and it has done a great job,but I have an actual Malware removal disk I used on another computer and it cleared it up quick,but with McAfee on the 780 would there any settings that need to be changed,turned off etc if I decide to run the Malware removal disk ?  I did manage to last night get some junk removed and had the C drive up to 11.2 gb instead of 0 and this morning when I turned it on I clicked on my computer and the 11.2gb went away back to 0..

Good afternoon . I received a response to my post earlier today about my Optiplex 780 saying the person who posted said they first check out the voltage on the battery,and then some other tests.

I tried several times last night to set the time and date on the 990 and it kept going back to 2011,so I put a new battery in it and changed the date and time and all of a sudden the computer started running like new again,I got to download Chrome and searching and it works perfect..so the dead 2032 battery was all that was keeping it from basically doing anything,so I got lucky ! I am going to load the McAfee 2019 on it and it will be ready to go..Thank you for all the info,I did learn a few things and will be here reading posts/threads daily,I need to smarten up a lot and be able to fix my own computers.