I have the same issue, but have not been able to find any solution on the Adobe site. Were you able to fix your issue?
I have not found an answer to this problem, though it hasn't been a problem lately. I now send the output of the vspider.exe process to a log file and can check the status of the index job. I index nightly, so if the process is running at anytime, I can look at the results of the index job in my log file. This might give some clues. I have a feeling I had a corrupt index and vspider was choking. Try rebuilding your index from scratch.
I don't know what might be causing this, sorry. But one thing to consider is to not run the vspider process on the same machine as that which is serving your site. That way, if it gets bogged down, it won't necessarily be a performance hit for everyone else trying to use your site.