External HDD - Extreme lag after mount
I have a 500GB external hdd, and every time I mount it for the first time after booting and try to view the contents, it lags for a LONG time - anywhere from 30 seconds to several minutes. I suspect there are some corrupt files, and I know that there are a few corrupt folders, <0 file sizes, etc. If this is the problem, I need to know what the best utility is to fix this. It's almost full, and although about 1/2 of the data isn't absolutly necessary, the other 1/2 is rather important, so I can't loose it.
Any ideas? (I DID google this, but I'm short on time, and didn't find anything within the first few minutes.)