Like the title says, I'm having problems with the USB linking - not quite sure why, although I think maybe because of MSD8X and USB8X. 
Here's what I know:
 -the port itself works fine (it links [when it wants to], and will not have any problems for a while, but every so often it does not want to link to anything [e.g. other calcs, computer, etc.])
 -MSD8X seems to trigger the problem - when I first plug in a flash drive, the whole system freezes (keys don't work, lcd freezes); then, after a few seconds, the calc returns to normal - I can navigate through menus and such.  But running the MSD8X app causes something to go wrong - A blinking cursor appears in the upper left hand corner, the apps menu does not get erased, and navigating to other menus pastes them to the "background".  Pressing clear does nothing to erase the "background" - the only way to fix it is to shut off the calc and turn it back on.  Afterwards, USB linking with other calcs and what not does not work.
 -setting the calc in self-test mode seems to fix the linking problem.

This app should work - I tested it on my 84+ - it works fine.  Also, the calc I am running this on (84+SE, OS 2.43, and Boot Code 1.00, with both MSD8X and USBDRV8X on it) has the extra ram pages.  What is going on?  Is there any way I can fix it?  Any help would be appreciated. TIA

try a ram clear that had happened to me b4 and a ram clear fixed it also what brand flash drive as some are incompatable

Brandon was right - it was the batteries.  Even though I never got the message saying they were low, I was using two different brands of batteries.  I swapped them out, and now it works fine.

Thanks everyone for helping!

Bit of a necropost, but...

IT'S NOT WORKING AGAIN!!!

(and this time it's not the batteries )

Any suggestions?  I know the flash drive and all the other stuff I'm using works (it works on my regular 84+).

Help?

On your regular 84+?  I think that usb8x uses extra ram pages, so it might be that you don't have them and therefore can't use it.

I have a TI84+SE without the extra RAM pages and USB8X/MSD8X works perfectly for me.

MSD8X does require the extra ram pages. I remember brandonW saying before that he was amazed that people got it to work on calculators that didn't have enough ram. I guess the only explanation would be if there aren't many files on the flash drive so that the different buffers don't overflow into each other.

Sorry for being so non-descript.  Read the first post to get a general idea of what is happening.

The strange thing is that this calc has extra ram pages - I don't understand why it doesn't load correctly.  I don't think it's a hardware issue, but I'm not sure what else to do.  Creating an external program to initialize usb (with usb8x basic libs) doesn't work (it strangely quits mid-execution) and creating one to run the app doesn't either.

Maybe it's because I have boot code 1.00?  IDK, but it is rather annoying.

I have OS 2.43 on there - when I got it from my friend, it had 2.21 on it - I know it won't run under 2.30 because it uses specific BCALLs from 2.30+.

Maybe I should mention this, but it is probably not important: it is a teacher edition (aka has the extra port above the LCD).