I had no trouble switching from 2.2.19 to 2.4.X. I now run 2.4.17 quite happily. If you're using Speakup with 2.4.5, I assume that you had to compile it yourself? If so, did you answer y for both PPP support and async serial support? Other than that, I've never seen the errors you described. Also, when you took out the Winmodem, did you nuke any modules it may have installed plus any calls to modprobe or insmod that referred to them?
