Virtualdub chokes

[vcmohan]

I use virtualdub to view the output of my avi files through Avisynth script. I find that whenever the script processing is fast (eg just Avisource (".....avi") and no other process is used) in the frame by frame mode it works fine but if I use play button after displaying some part of the file it chokes. At this time no control operates. Then after a while it starts to display and again chokes at some other point. If my script has a slower output (large number of avisynth processes) then this does not happen. What is the problem? My system is AMD XP 2000+, Windows XP Pro, 512mb ram, 40GB HDD

[vcmohan]

I got another problem. I am using Avisynth as a front end to Virtual dub. One of my plugin functions had an access violation error. In Avisynth I am processing clip 1 with plugin 1 which has no problem and then adding it with the second clip processing with plugin function2 having error.
The Avisynth script runs like this
<code>
DirectShowSource(".........Avi)
trim(clip,0,99)
clip1 = function1(......)
clip2 = function2(....) # this function has access violation error
clip1+clip2
</code>
When I use single frame advancer I expect that till frame 99 I should get no error . However I find that at about frame 80 I get access violation. If I remove the second function I do not get any error. Possibly virtualdub is getting frames in advance and reporting error because of it. But is it the way it should behave?