Suz
I use a bamboo with no problem at all. I initially installed it when using XPproSP3 and it reinstalled without any problem when I switched to Win7. I know thats of no help to you, but without a second pen to test if the first pen is faulty I can see no way to solve your problem assuming you have completly uninstalled and reinstalled your tablet to try.
If these tech people are adamant its your PC then ask them where the problem might lie as that would at lease give you a clue as to where the problem might be, assuming its not the pen after all.
Derek