I just had a bout with this same error myself. I had just put a new heatsink on my 1200 athlon machine. Went to boot into my Gentoo
invalid compressed format (err=1)
when trying to uncompress the kernel.
Just prior to replacing the heatsink, I had moved /usr from /dev/hde3 to /dev/hdf1, so naturally I thought my error was related to this. Trying to boot to the LiveCD from Gentoo
I got the same error. Did some Google
searching and everything pointed to bad ram, so I tested all possible configurations of my 3 sticks, same results. I finally decided to remove the cpu to see if I had smeared excess Arctic Silver 3 compound on the CPU, and lo and behold, there was but a scant bit of evidence that the heatsink was even touching the cpu core!
I removed the cheap heatsink I had bought and put it's fan on my better heatsink(who's fan was the reason I started this mess), installed the original heatsink and now everything is fine...whew! was I ever happy
I hope this helps you with your issue.