I observed the issue that IPCop is unable to install on storage devices which hold non-IPCop partition data already during my intensive testing with the 1.9.x line, but it seems that this issue is still with actual release. I got this issue also reported from some friends who use IPCop; actually a friend repoteded it to me who wanted to use a HD which was formerly partitioned by M0n0wall.
In all cases it helped to wipe the partion data with something like:
dd if=/dev/zero of=/dev/[h|s]da bs=1k count=1000
but I wonder why the IPCop installer cant correctly partion itself or wipe the storage device 1st - although it claims to do so with its warning .... :-P
its always troublesomely to 1st do the wiping with a LiveCD - specially when the firewall hardware is an embedded system with a flash where you need to disassemble the whole hardware in order to pull the CF ...
The dd is already there.
Problem is that we test for partition first using partprobe. partprobe does not seem to like some partitions. Erasing the partition before testing fixes that, at least for m0n0wall installations...