Receiving Error Messages on Start-up

Hello..I'm having a couple of problems and am wondering if they may all be related. On start-up, the following error messages appear:1) Cannot find file aucompat.exe (or one of its components). Make sure path and filename are correct and that all required libraries are available; 2) Could not load or run aucompat.exe in the WIN.INI file. Make sure the file exists on your computer or remove the reference to it in the WIN.INI file. No clue how to solve these messages. I am also having a problem running Defrag and Scan Disk. Defrag just keeps showing it is scanning for errors and Scan Disk just keeps
"checking folders ". I have run both of these before with no problem. Was wondering if the errors could be preventing them from running. I have Norton AV and last scan showed no viruses. Any suggestions..please, please..
Thanks in advance for any help. LWolly