Win 98se Compression agent

After my sons Dell computer with win 98se starts a box comes up that says.
Compression agent runs only on drive space 3 compressed drives.
To compress your drive,or upgrade it to drive space 3 format.
You need to run drive space 3.
Would you like to run drive space 3 now.
Yes No
He must choose yes or no to continue.
I had win 98 for a long time and I never recall seeing this. Can anyone tell me how he can stop this. How and where to change a setting or what. Thanks
Den

Edit - Failed to mention he has only one 30gb drive with 25.1 gb free.

 

I would run Startup.Cpl and check for any references to cmpagent.exe.

Else check your Scheduled Tasks whether it contains any entries like Compression Agent