Can't get poclbm to work for ATI Radeon 5770

I'm trying to get poclbm to run on a freshly installed Linux Mint Debain (LMDE) computer with an ATI Radeon 5770 card, but it's giving me errors that I can't understand.

Code:

savetheinternet@c ~/bitcoin/poclbm $ ./poclbm.py --user=$USER --pass=$PASS --device=0
Traceback (most recent call last):
  File "./poclbm.py", line 27, in <module>
    platforms = cl.get_platforms()
pyopencl.LogicError: clGetPlatformIDs failed: invalid/unknown error code

Also, I tried running it as root and it added another strange message. This time it's complaining about NVIDIA or something, but I don't have an NVIDIA card.

Code:

savetheinternet@c ~/bitcoin/poclbm $ sudo ./poclbm.py --user=$USER --pass=$PASS --device=0
FATAL: Error inserting nvidia (/lib/modules/2.6.32-5-amd64/updates/dkms/nvidia.ko): No such device
Traceback (most recent call last):
  File "./poclbm.py", line 27, in <module>
    platforms = cl.get_platforms()
pyopencl.LogicError: clGetPlatformIDs failed: invalid/unknown error code

Code:

savetheinternet@c ~/bitcoin/poclbm $ lspci | grep VGA
01:00.0 VGA compatible controller: ATI Technologies Inc Juniper [Radeon HD 5700 Series]

Any ideas?