I have created scripts using QTP(6.5) and saved them in Quality Center.I want to run these scripts in batch.I tried running them from 'test lab' in Quality center.But, I have come across the following issues which are interrupting the batch run :

1.A window pops-up randomly.It's name is QTPro.exe error.It contains the foll msg
The instruction at "0x01bb3f72" refernced memory at "0x0lefc5oc".The memory could not be "read".
Click on 'OK' to terminate the program.

2.Some tests fail to start.Quality center opens the test in QTP and does not start with the first step (which is clicking a link in the appln).QTP says 'Running' on the right corner but does nothing . I then manually click on 'Stop' in QTP and it proceeds to next test.
This also occurs randomly.

Any help is appreciated !!