From TDIClub

Front window regulator clips

For a4-platform cars through the 2002 model year, the front window regulator clips are known to fail often, especially on power window equipped cars. The result is that the window drops and cannot be closed.

A redesigned metal clip is now being used for replacements and new cars since the 2003 model year (however, there have been some reports of 2003 cars with the old type plastic clips). In the US, the warranty on the front window regulator clips has been extended to seven years from original in-service date, with no mileage limit, for a4-platform cars through the 2002 model year. Note that some of the oldest cars are now beyond this warranty extension.

Normal practice at dealers is to replace the clips on both sides if a car has been brought in with one failed clip. Some dealers will replace the clips if the door panel is opened for other reasons (e.g. door latch replacement).

A thread on VWVortex describes how to replace the front window regulator clips and door lock module: http://forums.vwvortex.com/zerothread?id=1015107

Door latch door open/closed sensor

The door latch includes the door open/closed sensor. Failure may cause odd behavior with the interior lights, warning chimes, power locks, and alarm.

Normal dealer practice is to replace the door latch; some do it yourselfers have managed to repair it.

A thread on VWVortex describes how to replace the front window regulator clips and door lock module: http://forums.vwvortex.com/zerothread?id=1015107