I thought I was installing an IOS upgrade, but now I can't access my AP1100s. Help! I need to go back to Autonomous.
I sounds like a TFTP problem (no firewall on your PC?)
Have a look at the details in the following threads that all have to do with TFTP. There are some great hints for troubleshooting TFTP problems from some of my favourite NetPros like ScottMac,Stephen from Cisco and Jack Young. The likely culprit may be that you need to uncheck "hide extensions for known file types" on your TFTP server;
Hope this helps! Good Luck!