NTOSKRNL

I have installed peachtree accounting software and it hung when I tried to uninstall it, so I called them and asked what to do, they told me to uninstall some hotfixes by microsoft, so I did and it worked. Untill I tried it on one and ran into some problems so I rebooted my machine and now I get the following error:

Windows can not find the following file
\system32\ntoskrnl.exe
Please reinstall this file

PLEASE HELP!!!!!!