Windows 98, hangs on splash

I have a rather strange situation with a Win98 machine. It hangs on the splash screen under normal boot circumstances and if I try to use a boot disk to get to an A: prompt it stalls as it says “Starting Windows 98”. If I enter safe mode and “start with confirmation” (#5) it gets to the first choice (installing compression driver) and again fails. I can not get this darn thing to boot no matter what. Anybody have any ideas?? The user said they suspect the drive is completely full but who knows?? I was going to boot to dos and delete tmp files etc to free up space but I can’t even get to an A prompt!! Help please if you can!! Oh did I mention this is the presidents home PC??

Thanks!!!