I just upgraded to Debian Squeeze and when launching Skype I got this nasty error.
Inconsistency detected by ld.so: dl-open.c: 643: _dl_open: Assertion `_dl_debug_initialize (0, args.nsid)->r_state == RT_CONSISTENT' failed!
I googled it and found the answer at the Debian Wiki.

http://wiki.debian.org/skype

I forgot that Debian has a quite good Wiki now. Use it.

Take care.