left and right channel audio reversed

Hi folks. I'm a newbie to reaper, and still figuring it all out, though not to DAWs in general. My previous one was a decade old version of Cakewalk...on an almost-as-old PC (I've finally upgraded to an iMac), so I have little doubt this will be an improvement. So far I'm pretty satisfied. One not-so-funny problem I'm having though...when I try and pan a track either left or right, the sound comes out of the opposite speaker. Yet when I play audio outside of reaper, seems everything is where it should be. I suppose the simple solution would be to switch the left and right cables directly from my audio interface when recording and mixing in reaper, then switch them back when I want to play the audio file...but I just feel like that's something I really shouldn't have to do. Any idea what might be causing this?

Have a look at your width setting on your master channel. If it's set to -100% your left and right channels will be reversed. Welcome to the forum. Steve

Well...your suggestion appears to have taken care of the problem, though I actually had to do the exact opposite of what you said. I had to make the settings -100% in order to hear it correctly! Very strange. The only potential problem is now, if I go to render the mixed down file, will it play back correctly? Or will the panning once again become reversed in the rendered file? I may have to test it out myself to know for sure...but I figure asking here might save me a couple steps.

Have you checked your device settings in the preferences? I am also curious about the width setting on your master channel... My master channel does not have a width setting, but the tracks can IF i set them for stereo pan. Is your routing from the master buss screwy?

Adding to Richie's reply. Take a look at the preferences for your soundcard (in Preferences->Audio) and make sure neither the input range nor the output range are reversed. Then check the width controls on your tracks. If you can't see a width control on the panel, right click the volume control (!!! no, I don't know why either) and you'll see it. Also make sure the phase alignment on your master track is set to normal (again, if you can't see it, right click the volume control) Steve

Actually...I believe I figured out the solution. Turned out to be a dumb mistake on my part, having nothing to do with reaper or my audio configurations. Plain and simple, my actual monitors were physically on the wrong sides! Must have happened while I was putting together my new setup. I just switched them back, reconfigured the audio back to the left and right channels, and all now appears to be well. I appreciate the swift responses though. Guess I made the right choice in going with reaper; this forum's a great resource.