I see the kernel you're using is 2.6.26-2. This kernel has a bug
in it wich causes the problem. The bug has been fixed since the 2.6.28 kernel. What you can do is using a little part of the squeeze/sid/unstable branch in your /etc/apt/sources.list and manually install the 2.6.29 or 2.6.30 kernel. After installing them you could quote the new lines in your sources.list file if you prefer to use the lenny/stable branch.
## US mirror:
deb ftp://ftp.us.debian.org/debian/ sid main contrib non-free
deb ftp://ftp.us.debian.org/debian/ testing main contrib non-free
## Latest drivers:
deb http://ftp.de.debian.org/debian experimental main contrib non-free
deb-src http://ftp.de.debian.org/debian experimental main contrib non-free
## Other Debian repositories
deb http://http.us.debian.org/debian testing main contrib non-free
deb-src http://http.us.debian.org/debian testing main contrib non-free
deb http://security.debian.org testing/updates main contrib non-free
After adding the lines mentioned above you could do a apt-get update
and install the kernel you want, for example using apt-get search linux-image
to see wich kernel images are available atm.