Johandk,
This is a quick, easy and cheap fix. It is the capacitors that have gone bad. Replace the 3 220uf/16v caps with new 220uf/25v and it will be just fine. It's a good idea to replace the 3 Instrument cluster bulbs while your in there.
Here is a link to the procedure:
http://bmwe32.student.utwente.nl/joh...dash_caps.html
Hope this helps, Good Luck!