Comment 46 for bug 476625

I experienced the same problem on my Acer AS3810T, on Maverick. However, it seems to be fixed in os-prober version >= 1.40 (see last message in the thread for this bug on debian.org, [1]).

I installed the .deb for os-prober (version 1.42) from natty, found here[2], and ran the commands:
$ sudo os-prober
$ sudo update-grub

Now, everything works fine :-)
I hope os-prober v1.42 can be backported to maverick.

[1] http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=589676
[2] http://packages.ubuntu.com/natty/os-prober