All of the audio paths are stereo - although the mic generates a mono signal, I have the mixer send the same signal to both channels but I typically record only one channel into the DAW. The other sources (the synths) generate stereo signals. The audio card generates stereo and records stereo.
Craig's comment led me to finding that I had somehow enabled both the Line In and the Stereo Mix. I turned off Stereo Mix and the reverb/loop effect disappeared.
The sampling rates for the sound card and Cakewalk are all 32 bit 44.1kH. I've checked some of the projects and they are the same.
Wave Profiler shows two lists. The first is MME Devices and shows a bunch of sampling rates as not available. That is followed by another list, also labeled MME Devices, with a bunch of sampling rates all being available. For example: 44100 Hz: Channels 1,2 -- Bits 16,24,32 -- OK. I have no idea what the first MME Devices list is for but the second one looks like I'd expect the sound card to handle.
I will check into an external interface. I have never used one but on earlier PCs I have used an internal sound card (not built into MOBO). One advantage of an internal sound card is the ability to record whatever you are listening to - like something off the internet. Sometimes useful.
Thanks for all the help. And I certainly got the message about a new sound card and appreciate the info provided by Cactus Music on the shopping list and Sweetwater audio interfaces.
Thanks,
Larry