When the problem arises it affects both the momentary and auto up/down switch positions. Just wierd that it only happens when the engine is running. Any other situation it works fine. That makes me think there is nothing wrong with the fuse, wiring, switch, or motor. You'd think there would be more electrical energy available when it's running, if it was a low voltage problem. I may try the larger fuse thing. However, it's not blowing the fuse so I don't think it's drawing more current than what the fuse can pass.

Over at MVS they've suggested a couple different system reset procedures. I'll probably try those also.

I read somewhere that there can be a correlation between the alarm battery and window function. I don't know about that one. However....... that being said, I was working in that area a few weeks ago to replace the W/W reservoir and the RH headlight (residual deer damage from a couple years ago). The problem did seem to start right about the time of that repair. Hmmmmmm.

Oh, yes, I'm familiar with the window re-calibration procedure. For some reason my wife's S80 needs it reset about once a year.
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Current rides: 2005 Volvo S80 2.5T, 2003 Volvo V70 2.4NA, 1973 Volvo 1800ES (getting ever closer to road worthiness)