Thomas, the Logitech mouse may also be the source of the issue. Logitech software installs its own system extensions ("kexts") and these have resulted in similar problems in the past at times. A quick google on "Logitech mouse OSX 10.4.7 " reveals quite a few people reporting issues with their Logitech mice after updating to 10.4.7.
There was a revised version of Logitech Control Center for Macs released in April this year, so if you haven't already got this installed it may be worth doing so. It is available from their download site
their download site
I note, though, that Logitech still only have qualified it for use with OSX up to version 10.4.6.
If you have a regular Apple mouse as well as your Logitech it would be interesting to know whether the problem still occurs if you uninstall the Logitech software and try using the regular Apple mouse for a while.
If not it may be worth trying
USB Overdrive instead of the Logitech drivers.
The combo update approach is worth trying too, though.
Cheers
Rod