hi,
ppreviuslly on this host: 
http://setiathome.berkeley.edu/show_host_detail.php?hostid=3093439(GenuineIntel
Intel(R) Core(TM)2 CPU T7200 @ 2.00GHz [x86 Family 6 Model 15 Stepping 6] [fpu tsc pae nx sse sse2 sse3 mmx])
I was positivelly running since months your 2.2B core2 optimized application.
Yesterday, after holidays, I have seen the announcement of 2.4 and I have installed the host I have at home. 
On the Vista one, the change from 2.2b Core to 2.4 core is not working and I have a lot of computation errors. 
http://setiathome.berkeley.edu/results.php?hostid=3093439but not all results are in error. 
I find also 
http://setiathome.berkeley.edu/result.php?resultid=595496860Computer ID   3093439
Report deadline   16 Oct 2007 14:25:56 UTC
CPU time   9420.323186
stderr out   
<core_client_version>5.8.11</core_client_version>
<![CDATA[
<stderr_txt>
Optimized SETI@Home Enhanced application
Optimizers: Ben Herndon, Josef Segur, Alex Kan, Simon Zadra
  Version: Windows SSE3 32-bit based on seti V5.15  'Ni!'
      Rev: (R-2.4|xT|FFT:IPP_SSE3|Ben-Joe)
    CPUID: 'Intel C2D Core 2 Duo (Conroe)'
     cpus: 1 cores: 2 threads: 1   cache: L1=32K  L2=4096K L3=0K
 features: mmx sse sse2 sse3 ssse3  
    speed: 1995 MHz  -- read megs/sec: L1=7512, L2=6354, RAM=3870
Work Unit Info
True angle range:  0.386177
Spikes Pulses Triplets Gaussians Flops
   0      2       7        0     22517751520048
</stderr_txt>
]]>
Validate state   Initial
Claimed credit   74.2937405464551
Granted credit   74.2937405464551
application version   5.27
So I don't understand if the problem is in the optimized application or in the data (results).
Havinng reached the dayly maximun number of results gotten, I was stopped. 
   Computer   Host   Date   ID   Message   Project
   Rocca_dell   ROCCA-PC   22.08.2007 08:24:58   64   Message from server: (reached daily quota og 62 results)   SETI@home
   Rocca_dell   ROCCA-PC   22.08.2007 08:24:58   63   Message from server: No work sent   SETI@home
So I have reset, detached and attached again the project.
For some day I will run the official 2.27 pgm untill you tell me what to do. 
Please, feel free to contact me by e-mail at francesco.forti at ticino.com 
for more info. 
Best regards, 
Franz
Edited lately: 
I have seen orher post about the problem but I don't know if the problems are the same.
I can add that I have seen that Boincview was showing me that vista/dell computer 
running the enhanced 5.27 duirng the "computation errors" but the pgm running
was the KWSN_2.4_SSE3-Core2_MB.exe one. 
Now I'm running the standard prograqm so "enhanced 5.27" is correct.
Somthing wrong in the app_info?