I had this problem a few times.

I have a P4-2.6GHz with HT that is 2 logical CPUs.

I have 3 attached projects now - CPDN, S@H and LHC. There are 4 S@H & 8 LHC@H WUs with "Ready to report" status and 1 CPDN WU currently running. I can not report finished WUs because S@H scheduler always not responded and now LHC scheduler also (Too many connections message some times)

When BOINC finished last LHC WU then BOINC hangs (I could not change BOINC pages and so on). Then I closed BOINC with Task Manager. After that I changed Global prefs from Max 2 CPUs to 1 CPU and restarted BOINC. And now it works (with CPDN WU).

This problem happened earlier when S@H Wus were finished. After that bug previous CPDN WU (with ~40 percent) was lost :(

This problem happened with BOINC 4.09 but 4.05 has not this problem (it seems).

Sorry for my terrible English :( I hope you can understand me and my problem.

<a href="http://www.boinc.dk/index.php?page=user_statistics&amp;project=cpdn&amp;userid=99"><img border="0" height="80" src="http://99.cpdn.sig.boinc.dk?188"></a>

Yes, I had this problem, too - I have two systems with two physical CPU's. It's a known bug, and happens when there isn't enough work for both CPU's to do from a given project.

Change your general preferences to use 1 CPU only, and then stop/restart BOINC. Once you have enough WU's waiting to keep your two logical CPU's going, you can go ahead and return to using 2 CPU's.

This happened with me mostly because of the SETI project - they've just started up and were/are having scheduler problems.

Try checking the disk space parameters in your general preferences and the relative resource allocations in your project specific preferences as described in the <a href="http://climateapps2.oucs.ox.ac.uk/cpdnboinc/quick_faq.php#f">FAQ</a>.
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Thank you both for your replies.

I think there is a bug in BOINC GUI and BOINC dev team should know about it.

I have at least 5 Gb of free disk space;
my params are:
Use no more than: 10 GB
Leave at least: 0.1 GB
Use no more than: 50% of total space

so I think there isn't a cause of this problem.

<a href="http://www.boinc.dk/index.php?page=user_statistics&amp;project=cpdn&amp;userid=99"><img border="0" height="80" src="http://99.cpdn.sig.boinc.dk?188"></a>