Bug detected
I just found the reason for my problems: since i use a single Opera profile and i always installed it with the Classic installer, all my Opera files are located on the D partition, including the user profile and Spybot 1.6.0.30 doesn't have the capacity to find the files there by itself. I have used this setup very well for the last 2 years and , since the problem has appered only after i upgraded Spybot, this is clearly a bug, in this build only.
How i discovered that: when i updated Opera today to the latest build i forgot to use the single profile option so a Opera profile was created at C/Docs and Set/user/App Data/ which was detected and immunised. After reinstalling the way i wanted (single profile in D) Opera has dissapeared again. This also explains why Firefox was immunised: even if it was placed on a stick, by running it it has created a clone user profile in C/Docs and Set/user/App Data/ (actually this is the reason i've abandoned it, a lot of wasted space and constant backing up of the profile from the hd to the stick).
So the correct form for my question is:
Is there a way to point Spybot to the correct location of the user profile files?