Time out of sync when editing files

[Starionx]

I recorded an HD broadcast and edited out the commercials. When playing the end of the file minus 15 seconds, the total file length shows as 49.55 and the time played shows as 49.50. The file plays until the end, but the time elapsed has already got to the total time about 10 seconds ago.
Basically, it seems the algorithm needs some tweaking to work out the real length of the file after edits have been made.
(apologies if this has already been pointed out).