uTorrent fails with "too many open files"

[joncage]

I have a virtualbox running Ubuntu (Kosmic Koala) with a Windows XP SP3 guest.

I'm trying to run uTorrent on the guest O/S and it's fine to begin with - torrents start okay but sometimes immediately and sometimes after a few hours it pops up saying "Error: The parameter is incorrect".

I've checked the virtualbox logs and see quite a few entries like this:

{{{207:50:46.297 SharedFolders host service: Cannot open '/drv/software/ubuntu-9.10-desktop-i386/~uTorrentPartFile_15DC5000.dat' -- too many open files. 207:50:46.298 SharedFolders host service: Cannot open '/drv/software/ubuntu-9.10-desktop-i386/~uTorrentPartFile_15DC5000.dat' -- too many open files. 207:50:48.247 SharedFolders host service: Cannot open '/drv/software/ubuntu-9.10-desktop-i386/~uTorrentPartFile_15DC5000.dat' -- too many open files. 207:50:48.248 SharedFolders host service: Cannot open '/drv/software/ubuntu-9.10-desktop-i386/~uTorrentPartFile_15DC5000.dat' -- too many open files. 207:50:49.280 SharedFolders host service: Cannot open '/drv/software/ubuntu-9.10-desktop-i386/~uTorrentPartFile_15DC5000.dat' -- too many open files. 207:50:49.281 SharedFolders host service: Cannot open '/drv/software/ubuntu-9.10-desktop-i386/~uTorrentPartFile_15DC5000.dat' -- too many open files.}}}

shutting down the virtualbox service and re-starting it normally does the trick if the guest is shut down first. I use the server to host software I write so having to go in and reboot all the time is (as you might imagine) rather frustrating!

I noticed one log entry suggested running "ulimt -n". Note that there's a type in that error message by the way. I ran:

ulimit -n 2048

...on the host (it was originally set to 1024) but that didn't seem to make any difference.