Reverb and Aux not bouncing to disk (NOT LLM)

[noevenable]

I'm totally flummoxed. Pro Tools has worked great for me for many projects, and I haven't changed anything in my setup. This just started happening out the blue. Here's the problem:

Problem 1:

I've got my mixes set up like I want them. I try to bounce to disk. I can HEAR the reverb on the vocal, so I know it's there. But when I listen back to the bounce, the vocal is dry. I didn't have Low latency monitoring on (searched the forums and learned about that possible fix.) But I even tried turning it on, trying a bounce, off, trying a bounce. Turned computer off and on, which helps sometimes with error messages. That didn't help...

Setup is this:
I'm using D-verb plug in, which I have as an insert on an aux track, set to recieve sends 1-2. My tracks that need reverb are bussing to that track on sends 1 -2. Output is the default "Main Out", never been changed.

Problem 2: Possibly related, and maybe a clue as to what's causing the above? Yesterday I was mixing, and had another weird problem. There are a couple of tracks which I recorded via Reason. (That is, now they're just audio tracks, but they are set to receive from bus 3-4, which was how I was routing the Reason aux track I'd created.) Like with the reverb, I can hear them when I am listening to the track bouncing. But when I listen back to the bounce, they're not there. SO... I monkeyed around, and found a fix for this. It's so weird, but here it is - I figured out that I could ONLY hear the reason tracks if I was sending them to reverb via bus 1-2. So I just bussed them all through the reverb, and managed to get them on the tracks that way.

But now that I can't even get reverb on my vocal tracks, I'm at a standstill, and naturally I have a deadline today. SO FRUSTRATED!

Can anyone help me?

Setup is this:
iMac (21.5 inch mid 2010, 3.2 GHx Intel Core i3 processor, 4GM 1333 MHz DDR3 RAM, OS Mountain Lion, Pro Tools interface is the MBox Pro.)

And I know it's an old computer, but I've mixed, like, 10 albums on this over the last two years and never encountered this problem.

Thanks for any help you can offer!

[noevenable]

One thing to add. I went back and listened to all of the 23 songs I've mixed over the last few days. This problem exists on all but three of them. Those three were all made from a separate file. (Whereas all the problem ones are being individually bounced out of a larger file that contains all of them.)

So it's definitely something in the way I have the file configured. What's so weird about it is that I'm not aware of anything being different bewteen the two files. The only thing I am aware of having changed is the CPU usage limit, which I was upping to see if I could eliminate an error message I kept getting. (I can't remember now what that error message was, unfortunately. But I think it was running out of CPU power, since it kept telling me to icrease the CPU limit.) (Turned out that didn't help, but restarting the computer fixed that problem.)

[noevenable]

It's FIXED! Thanks to all the friends on FB who saw my query there and responded. I fixed it by changing the default bounce source, in case anyone else is having this problem.