Recently, I have had similar problems with timed loops (LV8.0.1/W XP). According to NI's answer, this is linked to hyperthreading. Unfortunately, until now, my question if this incompatibility is a bug or not remains unanswered. Because my application is critical, I have replaced all the timed loops with while loops even if the crash didn't appear during a short test with disabled hyperthreading.
Hope this solves your problem.
Here is an extract of the exchange with JR Andrews from NI :
04/04/06
The preliminary investigation of the issue indicated that it may be due to hyperthreading (or having dual processors) and that disabling hyperthreading resolved the issue as a potential workaround. If you have the time and ability, I would be interested to know if you were seeing the issue on a hyperthreaded machine and if disabling hyperthreading does in fact resolve the issue for you. I can then pass that information on to the developer to assist them in fixing the issue.
Regards,
JR
JR Andrews | LabVIEW Real-Time & PDA Product Support Engineer | 512-683-2820
05/04/06
Even though your computers only have 1 processor, that processor may be using "Hyperthreading" to make it appear to the OS that there are 2 processors. You can check this by looking that Performance tab in the Windows Task manager or at the number of processors shown in the Device Manager. I've attached a screen shot of my system which is a single P4 processor which is hyperthreaded. Disabling the LV option for "Run with Multiple Thread" would probably not have any effect because to Timed Loops are always their own thread and that setting only applies to non-timed loop LabVIEW code. So I wanted to clarify that double check that your machine indeed does not have hyperthreading. To disable hyperthreading, you can go into the BIOS and you should be able to disable it. You can always go back and enable it again too.