I did check both pools' websites; I my worker showed no shares completed.

I was using the AMD APP SDK v2.1 to do my mining. I tried upgrading to v2.4. Unfortunately, cgminer built on this machine under v2.4 produced a segmentation fault; poclbm, meanwhile, kept claiming that PyOpenCL was not available (despite the fact that it was fine before). By happenstance in mucking about with the environment variables, I accidentally got things running... but it's not pretty. cgminer still won't work, but poclbm will run if I set LD_LIBRARY_PATH to the v2.1 SDK but set the ATISTREAMSDKROOT to the v2.4 SDK. I'm not sure why this strange hybrid environment is working, but it is. Unfortunately, it's working at a reduced hashing speed: 167MH/s instead of 175MH/s. I'll live with that for now.
Also, cgminer was behaving strangely; I tried to use "-k" to set the kernel but it ignored that flag and went with phatk (which it then complained about because it seemed to think I was running SDK v2.6, which I hadn't even downloaded). Fun times. :-P