I am having some weird issue here.
Everytime I try to install a CM7 nightly from CyanogenMod Downloads, I get an error. I am currently running the latest stable release.
The error I get in CWM is:
assert failed: run_program("/tmp/check_kernel") ==0
E:Error in /sdcard/CM7 Files/cm-7-20120715-NIGHTLY-shadow.zip
Checksums match, and this happens on any of those nightlies files, downloaded directly to the phone or to my Windows 7 PC and then moved to the phone.