It might be to early to declare victory, but at least the problem did not occur for two or three days now (I did restart only once, though, as for the rest of the time the iMac was in sleep mode, so everything has to be taken with a grain of salt).
I thought that the problem did not occur initially after switching to Yosemite, so I tried to race back what kind of software installs etc. I did afterwards. Here is what I came up with:
- removed MenuMeters from Preference Panes (V 1.7 I guess)
- installed iStatMini from the AppStore as it should provide similar functionality as MenuMeters in the notification center
- updated the Wacom driver to Wacom Tablet Driver 6.3.10-2
- I had no clear evidence that this was cause but I removed iStat Mini from the Notification Center... I remembered that I had some weird problems with iStat Menus (iStat Menus 5.03)some time ago, so this a kind of 80% blind troubleshooting attempt
- and installed the latest version of MenuMeters 1.8.1
And that's it.
So the question is, I guess, does anybody here use a combination of
- MenuMeters
- iStat or iStatMini
- Wacom driver
so that the culprit can either narrowed down (or the theory rejected...)
Martin
UPDATE: I also removed the Deliveries widget from the Notification Center, btw, as it nagged me by continuously asking for access to the keychain.