Labview crashes without any warning or error messages

[Gyro]

Hi,
I have been using Labview programs for the last 2 months without any problem. All of a sudden the program has started crashing while running. There are no error messages on the screen. The program runs for long hours and during my intermediate inspections i find that Labview has closed without any sign on the computer. This has happened about 2-3 times in the last week but before this there was no such problem. Also this problem is not specific to one program alone. There are other independent modules that have faced the same situation. No two programs are run simultaneously, and the programs use only serial (one of the program also uses parallel) communications with connected devices.
Any suggestions to troub
leshoot / diagnose the problem will be highly appreciated,
Thanks
Gyro

[Gyro]

CONTINUTED FROM ABOVE:
I stuck with the computer to see what the problem was. The application closes with a brief windows error message. The log file shows a 0000005 "access violation" error.
Most Importantly this also occurred when i just opened the program file without even running it !!

[LarsRoe]

The access violation is a common and broad error, and by itself isn't enough information. If LabVIEW crashes every time when opening it, the VI is probably corrupt. Can you drop the VI as a SubVI onto your block diagram?

[Gyro]

Thanks for your comments. I can use the vi as a sub vi. The error/crash occurs randomly (anywhere from a before running the program to about 8hrs after starting it). Improtantly i have used this program for about 15 times without any problem. The same error is also occuring for other programs. And all of these errors have started occuring in the recent past 3-4 days. Any clues as to what might have triggered this?