Mines getting harder and harder to reset too.
I've asked about it here before. Was told probably "bad capcitors".
I'm pretty sure it's a bad micro switch though, since it shows no other signs of bad Caps and it's a intermittant problem.
You should be able to get a read out without the key in the ignition when you press the reset button, and that don't work either. Which makes me think a bad micro switch.
I'll do the Caps one of these days just to varify it, since it's a cheap fix. Hopefully Digi-key has a compatable switch too, if the Caps don't fix it.
1991 525i M50 5 Sp.
N.California
America is all about speed. Hot, nasty, badass speed. -Eleanor Roosevelt