Cron Search failing and Fast View Search not working

Hello,

I have a strange issue with the search index, cron and the Fast Search.
And it is becoming a nightmare!

I have done all that was explained on other related issues (cache, semaphore...) but nothing is changing.
Cron is hanging on the Search (index), and when it is hanging, the Fast Seach doesn't work anymore.

These are the log entries for the cron:

cron 27/07/2009 - 14:00 Attempting to re-run cron while it is already running.
cron 27/07/2009 - 13:15 Attempting to re-run cron while it is already running.
cron 27/07/2009 - 13:00 hit search cron

between 13.15 and 14.00, fast search isn't working.
And it is as regular as this...for all the cron runs (scheduled each hour).

By the way, the search index table has duplicates. I have also patch and created the new index as mentionned in the install of the Fast Search.

Can someone help me?

Thanks in advance

Thomas