Help required please.

Dimension XPS T700r running Windows 98 SE

On shutdown get following error message;

run_time error R6009
-not enough space for environment
Press any key

Doesn't appear to be causing any trouble but I
don't know what may be happening that I am not aware of.

Have run Dell Diagnostics - everything passed.

Tried regscan /restore in MS-DOS but dates of .cab files are too recent. I power down at night.

Have done diskscans and defrags etc.

Am at a loss on what I should do.

Can anyone help please? I'd be very grateful.