What OS are you using and which version of cusp?
Several possible workarounds:
1) Try specifying executable (leaving other fields: Initialization
file and Path to system difinition, empty) in Preferences->Lisp-
>Implementations
2) Try putting sbcl into cusp directory:
Find jasko.tim.lisp folder in eclipse/plugins folder
create sbcl folder there: i.e.
eclipse/plugins/jasko.tim.lisp/sbcl/
copy sbcl executable and sbcl.core into root of jasko.tim.lisp/sbcl
folder.
Then copy to the same folder other folders:
jasko.tim.lisp/sbcl/asdf
jasko.tim.lisp/sbcl/asdf-install
jasko.tim.lisp/sbcl/sb-aclrepl
jasko.tim.lisp/sbcl/sb-bsd-sockets
jasko.tim.lisp/sbcl/sb-cltl2
jasko.tim.lisp/sbcl/sb-cover
jasko.tim.lisp/sbcl/sb-executable
jasko.tim.lisp/sbcl/sb-grovel
jasko.tim.lisp/sbcl/sb-introspect
jasko.tim.lisp/sbcl/sb-md5
jasko.tim.lisp/sbcl/sb-posix
jasko.tim.lisp/sbcl/sb-rotate-byte
jasko.tim.lisp/sbcl/sb-rt
jasko.tim.lisp/sbcl/sb-sprof
jasko.tim.lisp/sbcl/site
jasko.tim.lisp/sbcl/site-systems
Restarting eclipse and start cusp. Report here if you still have
problems or this was successful.
Possible reason for this problem: The only officially supported way to
run sbcl right now is from jasko.tim.lisp/sbcl folder. Lookup of path
through environment variable was experimental and I tested it only on
WinXP. More robust ways of starting lisp is planned for after the 1.0
release. Sorry for inconvenience.