(found the solution to this but reporting it in case there's a better way to handle the situation in future versions of SLIME)
I've been using Slime with CLISP on Windows (just as a learning environment) and love it so I thought I'd get an environment working with my iMac as well. I tried to get CLISP working but it threw me an error so I thought I'd try again and install OpenMCL instead.
However, it also threw me an error (reproduced below) which I eventually tracked down to my ~/.slime directory causing me problems. Apparantly running slime originally with CLISP caused a problem. When I removed ~/.slime and started again everything worked fine.
For the record (in case anybody else is googling like me), the error I got was as follows:
Welcome to OpenMCL Version (Beta: Darwin) 0.14.2-p1! ? > Error in process listener(1): Incompatible lambda list in #<STANDARD-METHOD\ SWANK-COMPILE-STRING (T)> for #<STANDARD-GENERIC-FUNCTION SWANK-COMPILE-STRING\ #x6381456>
While executing: CCL::CHECK-DEFMETHOD-CONGRUENCY Type :GO to continue, :POP to abort. If continued: Remove 0 methods from the generic-function and change
its lambd\ a list. Type :? for other options. 1 >
Hope this is of some use
Ian Cottee