Changing the value for SocksPort requires 2 edit cycles.
Many TBB-users have complained about "The proxy server is refusing connections". I MAY have found the root cause, but this is certainly a bug.
How to reproduce the bug:
Start with two edited torrc files. (Caveat/note  and  below). Make sure that TBB starts and connects to the internet properly using one of torrc files. In the Vidalia Control Panel press "Stop Tor" -> "Settings" -> "Advanced". Change the value for "Tor Configuration File" to point to the other torrc. Press "OK" to close window. Press "Start Tor". Wait... Open a link in TBB to, say: https://www.torproject.org/ Here I get "The proxy server is refusing connections".
I solve the problem by:
- stopping Tor.
- opening the torrcfile.
- check the value for SocksPort: it is ALWAYS 9050 !!!
- edit the value to SocksPort 9150.
- save the torrcfile.
- start Tor again.
- try to open https://www.torproject.org/ in TBB.
- FAIL again with "The proxy server is refusing connections".
- stop Tor.
- edit torrcfile, set SocksPort 9150. save torrcfile.
- start Tor.
- Open https://www.torproject.org/ = SUCCESS.
What is interesting is, when I:
- stop Tor.
- change settings to point to the different torrc file.
- start again. the result is THE SAME!!! "The proxy server is refusing connections". So I check the value for SocksPort in the currently active file, it is: 9050 !!!
 Not sure it is required for these two torrc files to have different settings at all, would need several hours more to find out.  Not sure if these torrc files need to contain the old values SocksPort 9050 or not. In my experience it doesn't matter, everytime I edit and save the values to 9150 - something "behind my back" changes it to the wrong value.
Conclusion: Switching back and forth between two or more torrc files results in failure to connect to the internet. Despite always editing and writing the correct SocksPort values back. Something inside TBB or Vidalia defaults to the wrong value, and neccessitates two edit cycles.
Don't tell me it is supposed to behave like this. Do tell me if you can't reproduce this behaviour. I'll check back in a week or so.