I am using remote debugging on a Win2k server. The debugger keeps freezing up while stepping through a script. It happens on a different line in the script each time, or in various scripts altogether (sometimes it freezes on the 1st php page, sometimes on the 3rd, etc.), so I'm not sure where to even begin troubleshooting.

I'm 99% sure that the debugger is not involved as otherwise I would see ~ 10000-20000 similar claims everyday, while actually yours is the first. Isn't strange ?
As a troubleshooting, you'd look at the network performace counters to see if you have dropped packets or packets with invalid crc, etc. Have a look at the server statistics too. Also, make sure you have good connection with the server.

Actually I have the same problem. I'm running PHPEd 3.3 w/ DBG 2.16.3 and when I'm stepping through code, it often freezes. This happens when I hit Step Over, Step In, Run To Cursor, etc. It doesn't lock-up, but the blue line indicating the current line of execution disappears, as if it's running forward, but nothing happens from then on. It doesn't stop at any additional breakpoints (if I have any after the line it "broke" on), but neither does the final output for the page ever appear.

My only recourse is to hit Stop, and maybe try it again. But it makes it very difficult to figure out what's going on, because as I said, there's no output. Truthfully, I've found the whole PHPEd/DBG setup quite finicky. Sometimes it seems to work well. But other times I'll set a breakpoint, hit F9 on a page, and then at the breakpoint, sometimes variables that should be in the Locals paine aren't. Or othertimes I'll move my mouse over a variable in the code window and a tooltip will say "undefined," yet the same variable is in the Watch window and displays a value for the same variable? And of course, the biggest problem, after many breakpoints, when I try to move on (F4 Run, F8 Step Over, etc...anything really) it just hangs or freezes and no output appears.