I suspended the project (not a task) just after the beginning (a few seconds). The boinc client listed it as 'suspended' but looking at the task manager I saw the application listed there (even if not actually using cpu time). This happened only in the very first seconds of the run. After the first checkpoint the task correctly disappears from the task manager if suspended. I noticed this on W7u x64.

It doesn't make sense to me because we fix the problem of critical section since the 0.03 version. Moreover, before writing the checkpoint we don't have any critical section!
We will surely investigate this issues (already saved in the to-do list ;-)