The really puzzling thing about this is that you have an AVI file which plays OK in other applications, but Studio doesn't play a section of the audio.
There are a lot of things - firewalls, virus scans and lots of other programs operating in the background that can interfere with a capture operation. I've had audio and video go astray due to such interference. I've wound up with a video file with no audio or frozen video.
What I haven't come across is an affected file that only shows the defect when played in Studio.
Why not try the capture again? I think that might be better than
trying to sort out the weird problem with the file you have now
Looking at some of the things that may have caused the audio defect, the key things when capturing in my experience are:
1. to create a really simple environment (take out the competition);
2. capture to a disk which is separate to the PC operating system disk;
3. and which has been defragmented .
In order to make sure you have taken as many potential disruptors out as possible, there are two methods recommended. (Before you do either of these, turn your internet access OFF. Otherwise your PC will be vulnerable to attack.)
Method 1. Use MSConfig (started in "Run" on XP) and turn off all background apps: or
Method 2. As per Towbar's post elsewhere, use Enditall to close the background apps.
Method 2 has the advantage of not requiring a restart.
Last step - disable any other network connections.
That's all I can think of at this stage.