It took me hours and hours to figure out that the reason was probably a few bad clusters on the HD although the clusters don't seem to be related to a file used upon boot. (Most of then were related to Windows system backup files and one on disk D to a data file without importance.) So it looks really strange and I'm not sure that they were the cause for my issues; maybe I just fixed something else without knowing.
Anyhow I couldn't be online tonight. Sorry.

If you don't see me online soon, then you'll know why: some computer troubles again likely.
I'm going to take some time to check all my backups and do some more: I have all AP and AO related stuff on this computer... I don't want to lose anything.