i have a compaq thats about 4 years old and when i moved it from one house to another it no longer starts. sometimes it will get to the home screen and other times it will freeze on "loading your personal settings". As soon as i do get to the home screen i cant click on any icon even tho my mouse is moving. i cant "tab" into the icons ether. then if i hit alt ctl del it shows system at 99 and then by then its already froze. there was a screw bouncing around it there too. dunno if that means anyhting. please help!

:-/ I think you might want to remove that screw. After, of course, you disconnect the power plug. You must make sure to avaoid touching any of the components, if you are inside the case, without being properly grounded (hand on metal case, foot on solid ground will work). Try to fish the screw out w something that doesnt conduct electricity and dont touch the motherboard especially.
After you get the screw out, you may want to try a safe boot. THat is, while the system is initially loading up (called a PowerOnSelfTest or POST) hit one of the F keys. Usually F1 or F2 to enter BIOS and F8 or
F10 to enter the boot options screen. If your not sure, just hit the Right most "F" keys and you are bound to get in!
About the keyboard and mouse, are you plugging them in via the backside of the PC? Does your mouse have the Mini-Din connector connector or a USB? With the USB, you cold try to plug into a different port other than your parallels.
Windows user??
*Here's a hunch* If you can boot to safe mode, then you may be able to select the 'Run' feature from the start menu. Enter 'msconfig' (no quotes) in the Run box and hit enter. From there you will be able to choose which programs run on startup. I would go with the diagnostics option.