Inspiron 1545 keeps crashing

Hi all, I have a Dell Inspiron 1545 laptop. Every time I switch it on now, I get about 2 minutes of use out of it on whatever program before it crashes.

I thought this was originally due to a piece of software called "Orange Business Everywhere" (for USB modem) , which I uninstalled but it has made no difference. I managed to do a spyware check and delete the spyware, but I cannot do a virus scan because the computer crashes mid-scan.

I have tried a system restore at 2 restore points, this has not worked. I have tried reinstalling the internet software and now this does not work when it did before. Everytime I open it I get a message saying "Installgui.exe- windows is searching for a problem". I have tried the internet software and modem on a mates laptop and it works fine.

Google Chrome, Orange Busines Everywhere, Firefox and BBC iplayer all dont work.

I once got an error messages on google chrome saying "preferences corrupted" and "Failure of security options".

Every time I restart the computer manually it does a disk check on startup.

Any advice would be much appreciated as I am completely clueless as to what to do.

Cheers

Chris Barnes