Is this the full text of the error message you've been seeing? -->
“We apologize for the inconvenience, but Windows did not start successfully. A recent hardware or software change might have caused this. If your computer stopped responding, restarted unexpectedly, or was automatically shut down to protect your files and folders, choose Last Known Good Configuration to revert to the most recent settings that worked. If a previous startup attempt was interrupted due to a power failure or because the Power or Reset button was pressed, or if you aren’t sure what caused the problem, choose Start Windows Normally.”
What version of Windows are you running?
You mention that "it pops right back to the safe mode window where I cannot do anything" --- do you mean that the PC 'freezes' at the Safe Mode menu? Or that you enter Safe Mode, and then it freezes? Or that you enter Safe Mode & can't do a particular task that you'd like to do?
The error message can be caused by many different things. It could be a hardware problem or a software problem. Did you recently add a new piece of hardware or software? If so, post that info here. If you recently plugged in a new USB device, for example, remove all external devices except your monitor, keyboard & mouse, and see if the PC boots OK then.
If you have a version of Windows that has the System Restore utility (Window Me, Windows XP), and you can enter Safe Mode successfully, you can try using the System Restore program, selecting a 'restore point' from before your recent trouble. Start-All Programs-Accessories-System Tools-System Restore.
How old is your Compaq? If you suspect parts failure, you can run some diagnostics. Many Compaqs have diagnostics programs built-in, & you can see a menu of choices by pressing the F10 key as the system is powering on. There are also third-party tests you can run to test the memory ( http://www.memtest.org
) and hard drive ( http://tacktech.com/display.cfm?ttid=287
) -- many such diagnostic tools are included in & can be run from a bootable Linux CD such as the UBCD ( http://www.ultimatebootcd.com
A big priority right away should be to save the important personal data on the drive (documents, photos, music, etc.). If you or a friend has a Windows XP system, try making a "UBCD4Win" CD, from which you can boot your computer (if it is mechanically sound enough to do so) and copy your important data off onto a USB flash drive, some CDs, or an external hard drive. ( http://www.ubcd4win.com
If your computer has a mechanical/electrical failure that keeps it from booting from a bootable CD, then you might need a technically-minded friend to help out -- have them remove the hard drive from your system, attempt to read it when attached to another computer, and save the files to removeable media. When saving files in this manner, it's also a good idea to scan them for malware before saving them.
Best of luck
. . . Gary