I haven't installed IrfanView and RegCompact.
FYI, that thing mentioning IrfanView and RegCompact was just so that others could try to reproduce the problem. It first popped up when I was testing RegCompact and getting screenshots ( see here
Most likely there are other combinations of running software that will cause ProcExp to crash as it starts up. That particular combination mentioned above was routinely reproducible but I am sure there are others.
What happened is that Mark ( the author ) was recompiling the System Internals applications and was in the process of switching over to VS2008 ( see here
) which killed off Win9x for good. Process Explorer was at v11.12 when it became official but it is clear from looking at the increasing filesizes above ( see v10.10 ) that he was already in the process changing over around the summer of 2006 when Microsoft assimilated the company, adding new #includes which showed up in the compiled EXE's as Microsoft EULA's and other stuff. The large bloat is partially from that and also from the fact that he was creating dual 32-64 bit hybrids ( a good thing ). There was also some GUI tweaks occurring most noticeable in FileMon and RegMon between versions 6 and 7 which caused some problems. So there are at least three or four influences in play.
Interestingly, some people apparently have no problems with ProcExp v10.xx in Win9x. So it may be case-by-case dependent on other variables we have yet to isolate.