I had the same problem once before with SMF on a windows based web server. PHP was not really written for Windows based servers, is sort of mdified to fit, and quite badly sometimes. After changing lots of php settings and not working, I moved the SMF install onto a Linux web server and all problems with CGI disappeared forever..!!
Also, how can you go through the process of chaning onto a new server and not upgrade to the newer version of SMF. 1.1.2 is listed as insecure and easily hackable. Those being blocked in releases 1.1.8 and later.