My Pansat 3500s does that sometimes. I think it may be caused by having too many Satellites programmed in (and turned on)? When it happens, it's usually after I go to a satellite that I keep OFF on the Satellite Position in USALS. I turn it on to go there because I've heard about something interesting that may have been found there, and it goes to it fine. But, if I forget to turn it back OFF and go somewhere else, sooner or later it doesn't go where I'm trying to get and when I check in the Menu's, Satellite SetUp, I find everything screwed up for this satellite I'm trying to get to, just like you mention, and I have to straighten it out. And then sooner or later it happens again, I find a dfferent satellite that it won't go to, and then discover in the Menu's, that it too is screwed up, I think because I still have too many satellites programmed in. At first I didn't know (and still don't, really) what was going on, but something made me think about it started when I added the Satellite that had been turned OFF. So I went to that satellite (which I rarely look at) and I turned it back OFF and haven't had any more problems. Don't really know if this is what was happening or this is what caused what was happening, but it seemed to quit when I took that added satellite back OFF. Maybe this is what your problem is? Good Luck!
Al