Volkswagen: 1999 VW Cabrio, fuse, corrosion

Question
First thing in the morning the car runs very rough, this is also the case when it is very damp after warm up it seems to run fine. Lately the alarm system will arm itself while I am driving, the interior lights will go on and off, the windows will go up and down. Now the passenger window doesn't work at all. Check engine light is on.

Answer
It's hard to say for sure, but it sounds like you may have a bad ground or power connection.  Driving along and hitting normal bumps can cause intermittant power spikes in this case, which can drive the computer crazy and make it do weird things like you describe.  Check the battery terminals for corrosion or loose connections.  Also any straps which ground the engine/transmission.  A loose contacting fuse, unlikely, could do it also.  Good luck.