Thank you for your advice. I changed the rest of my preferences to "on multiprocessors use 100 %", too. But Boinc still doesn't reply.
And that's what Boinc shows me:
06.10.2011 10:58:57 | | Starting BOINC client version 6.12.34 for windows_intelx86
06.10.2011 10:58:57 | | log flags: file_xfer, sched_ops, task
06.10.2011 10:58:57 | | Libraries: libcurl/7.21.6 OpenSSL/1.0.0d zlib/1.2.5
06.10.2011 10:58:57 | | Data directory: C
okumente und EinstellungenAll UsersAnwendungsdatenBOINC
06.10.2011 10:58:57 | | Running under account Administrator
06.10.2011 10:58:57 | | Processor: 2 GenuineIntel Intel(R) Celeron(R) CPU E3400 @ 2.60GHz [Family 6 Model 23 Stepping 10]
06.10.2011 10:58:57 | | Processor: 1.00 MB cache
06.10.2011 10:58:57 | | Processor features: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss htt tm pni ssse3 cx16 nx lm vmx tm2 pbe
06.10.2011 10:58:57 | | OS: Microsoft Windows XP: Professional x86 Edition, Service Pack 3, (05.01.2600.00)
06.10.2011 10:58:57 | | Memory: 2.00 GB physical, 3.85 GB virtual
06.10.2011 10:58:57 | | Disk: 97.65 GB total, 25.64 GB free
06.10.2011 10:58:57 | | Local time is UTC +2 hours
06.10.2011 10:58:57 | | ATI GPU 0: ATI Radeon HD 4350/4550 (R710) (CAL version 1.4.636, 512MB, 96 GFLOPS peak)
06.10.2011 10:58:57 | sudoku | URL http://sudoku.nctu.edu.tw/; Computer ID 5198; resource share 100
06.10.2011 10:58:57 | World Community Grid | URL http://www.worldcommunitygrid.org/; Computer ID 1742636; resource share 100
06.10.2011 10:58:57 | | General prefs: from http://bam.boincstats.com/ (last modified 06-Oct-2011 10:55:21)
06.10.2011 10:58:57 | | Host location: none
06.10.2011 10:58:57 | | General prefs: using your defaults
06.10.2011 10:58:57 | | Reading preferences override file
06.10.2011 10:58:57 | | Preferences:
06.10.2011 10:58:57 | | max memory usage when active: 2047.17MB
06.10.2011 10:58:57 | | max memory usage when idle: 2047.17MB
06.10.2011 10:58:57 | | max disk usage: 0.00GB
06.10.2011 10:58:57 | | max CPUs used: 1
06.10.2011 10:58:57 | | don't use GPU while active
06.10.2011 10:58:57 | | (to change preferences, visit the web site of an attached project, or select Preferences in the Manager)
06.10.2011 10:58:57 | | Not using a proxy
06.10.2011 10:58:57 | | Suspending computation - initial delay
06.10.2011 11:00:57 | World Community Grid | Restarting task X0940044890445200501191524_1 using hcc1 version 642
(also other projects won't reply to the dual core preference. WCG is just an example.)
I hope this will help. (: