Well, you definitley need to upgrade module-init-tools to v3.0 if you haven't already done so!! Look on the slackware website for a .tgz package, install it using pkg-tool. Otherwise things won't work right. Once that's done you're going to have to run the script
in a console to get a new modprobe.
Now this may or may not solve your problem directly, but - one thing at a time, now