Todays vehicles inlcudes more electrical systems than ever before.
Due to this, the alternator have to charge the electrical system "harder" around 14.5 Volt to remain a good battery capacity and load balance. Bulbs are made for 12V which can not handle the higher voltage that good. Unfortunately there are no 14.5 V bulbs on the market.
Volvo have developed a resistor cable kit which recudes the voltage to the bulbs, and the lifetime will be longer. This kit was introduces in production maybe from model year 2002 (I am not sure exact introduction time).
If alarm go off randomly then it is defective and has to be replaced. Sometimes alarm sensor is too sensitive, but at 2AM and if noone is near the vehicle then I think its more defective than too sensitive. Also note that some microwave ovens leaks, and if vehicle is parked close to kitchen, then the alarm may go off. Wireless TV transmitters may also cause false alarms since they use microwave band as well.
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