Using fglrx release 2.1.7979 (Catalyst 8.9), Xorg 7.3, Debian/lenny version 2.6.26-5 (kernel version 2.6.26-1-686), and the rrootage package on the Debian package archive.
With the above, rRootage segfaults at a few particular points. So far, I've found:
1. IKA mode 4A-3, after the enemy fires its first few bullets
2. PSY mode 1A-3, after the enemy fires its first few bullets
Unfortunately my lack of skill in the game prevents me from finding any more; however, I can say that the problem is not IKA or PSY mode in general, as other levels in those two modes work normally.
In all cases rRootage simply exits with the message "Segmentation fault," and no syslog, kernel.log, or dmesg messages give any more information. Also, when it does crash in those two cases, it does so consistently at that point; no amount of prior play changes when the segfault occurs, or what happens when it does.
Also, I tried the official binary; that doesn't work either.