It shouldn't make any difference to your search for keywords by purging your cache, as all that does is stores thumbnails to your photos. When you open a folder with photos in, then the thumbnails are displayed straight away rather than waiting a few seconds. When you put a new card of photos into your PC, then Bridge has to build a thumbnail view of all your photos, which only takes a few seconds. By purging your central catch it just increases the time for thumbnails to display when you open on of those folders.
Open Bridge, select File, Preferences and click on the Cache option and click the Purge Cache. As you open folders with photos in Bridge, then it will rebuild the thumbnail cache.
Thanks for the reply - in the past if I purged cache - then any search I did - returned no items.
Even if I was searching in the folder that was currently open - I could select by ticking the keword in the left panel - but if I did a keyword search by clicking on the keyword in the panel on the right, right clicking and selecting find - it would not find anything - until I opened each folder and sub folder in turn and waiting till it redid all the thumnail extrtactions.
Adobe sent a reply telling me to hold down control while starting Bridge and resetting all the preferences, then installing the latest update CS5 4.0.4
It now seems to be searchng when I use the find from the right side keywords panel - it is just taking forever!
If this does not work I will get back to adobe again and post any further fixes
DO you use lightroom ? is it worth trying it out - ?