As my work is, I have to deploy x-times some assembly in my GAC and test it.
Well once in a while my assembly folder just seems empty, And then I can't build / deploy my solution anymore.
Here is the trick: (It is not mine.. but the more places it is published, the easier you guy find it:)
Start your windows services management console (services.msc) and restart the Indexing Service and everything is back to normal.!
Cool... once agian.. it was not our fault... we where just working!