First, although it is not directly related, any changes made to 'omnirc.tmpl' will have no effect. This is a template file. The lines you referenced should be in a file 'omnirc' and it shouold have no filename extension.
Also, whenever you make a change to a 'omnirc' running on Windows, you have to stop and restart the DP INET service after saving the file
Here is what I found on your error, although most of these are for DP 6.2 and 7.0x
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In one case, this was caused by having a firewall turned on, where the debugs would show
[ 5] [MARK 3] in IpcConnectToProcessBase
Code is:3012 SystemErr: [10061] Connection refused <--------------!!!
Turning off the firewall, which was on the Network, in tyhis case HP Sec Blade firewall was enabled. Alos, if oyu have a local firewall enabled, it can cause this problem
I don't know if this is going to be your solution, since this started happening after upgrading to 8.1, but it is a known source for this problem. There 5 cases where a firewall was shown to cause the problem
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There were a couple of 'vssbar' fixes made, but, these were for DP 6.21, so probably not of much help
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If all the possible firewalls are turned off, you will need to open a case with the response center. You will need to run INET debugs, and collect the debugs from the Cell Manager, and the client where this is failing