You need to delete or rename the file logo.sys in the root directory of your boot drive.

You can use the system file checker to restore logow.sys and logos.sys from your windows 98 CD.
Click start | run and key sfc.exe and click OK.
Click on the restore a single file radio button and key one of the above filenames (logow.sys or logos.sys) and click on start.
You may need to point it to the win98 folder of your windows 98 CD or to the cab files on your hard drive.
These files belong in your windows folder, it should have that already filled in.