I currently noticed high hard drive activity and looked into it using procmon.
I found out that Steam is constantly trying to read the same key without success and doesn't stop, even after hours.
I contacted Steam support and followed all the steps proposed by the support guy, but nothing helped. I did a complete uninstall of the program, manually deleted remaining folders, deleted the appropriate registry keys and even used one of those strange FixIt programs by Microsoft.
It's not really slowing down my computer but it's causing very much had drive traffic and obviously an abnormal behavior. Has anyone faced the same problem before?
My system is Windows 8 x64 and I used the latest version of Steam.
In the meantime I re-installed Windows on new hardware... and the problem persists. This drives my crazy.