Computer Issues... UGH! Please bear with me!

So I'm not sure what is going on with my computer. It's crashed on me 3 times today and I can't seem to figure out what is going on with it. I talked to a computer repair person and he told me to run several tests on it to try to diagnose the problem. It's either a memory issue, power supply issue, or Windows issue. If it's a Windows issue I'm going to have to run a full re-install of Windows. Not fun... and will take me days probably just to save all of my programs and client information in order to wipe the system clean and start over. So please bear with me. If you have sent me an email and I don't respond right away I apologize. I only have internet access via my laptop right now and I can't get into my Microsoft Outlook from here. The CPU will be running tests for at least a day to get this all worked out and give me a starting point, so I may not be able to get back to people until Friday. I will get back to everyone as soon as I can! Thanks for your patience. In my business we live by our computers and all of my business transactions take place on it. It really stinks when something goes wrong because it can hold me up for days... ARGH!