HTC Droid Eris :: PC Not Recognizing My USB-connected

I USED to be able to transfer files to my Vista32 machine from my Droid Eris (and vice versa) perfectly fine.

WHAT USED TO HAPPEN:
1) Connect Droid Eris to computer via mini-USB/USB cable
2) A little ding from the computer indicates it recognizes something was plugged into the USB port
3) the "safely remove hardware icon" would appear in the system tray of my computer
4) A "USB Connected" Notification would appear up in the notification bar of my Eris
5) Drag the notification bar down and select the "USB Connected" Notification
6) A prompt would come up on my Eris asking me if I'd like to "Mount"...I would.
7) A dialog would open on my computer asking me if I'd like to "Open files to view folders" along with a bunch of other options. In "My Computer" I'd see a drive "F:" for the Eris
8) Move files to and fro
9) When done moving files: close out all windows, open the "safely remove hardware" and click until hardware could safely be removed, unplug USB cable

THE RELATIONSHIP CHANGING EVENT:
Then one day while the USB cable was plugged in and I was happily transferring files I noticed that the safely remove hardware icon wasn't there. Once I was finished transferring files I thought, "Oh well, I'll make sure to close out all Eris related files/folders and just unplug the USB cable." Apparently that was a mistake. (3,7,8,9 are different from before while 1,2,4,5 are the same):

WHAT HAPPENS NOW:
1) Connect Droid Eris to computer via mini-USB/USB cable
2) A little ding from the computer indicates it recognizes something is plugged into the USB port
3) NO safely remove hardware icon appears
4) A "USB Connected" Notification appears up in the notification bar of my Eris
5) Drag the notification bar down and select the "USB Connected" Notification
6) A prompt comes up on my Eris asking me if I'd like to "Mount"...I would. (after selected the notifications changes to read "Select to turn off USB storage" indicating that the phone thinks something has happened
7) NO dialog opens on my computer and NO new drive appears in "My Computer"
8) I'm NOT able to move files to and fro
9) I just remove the cable

BIZARRE UPDATE:
1) I select the "HTC Sync"
notification on my Eris (Really no reason to do this. I don't have HTC Sync installed on my computer and have no need to use it. Just thought I'd select it and see what happens)
2) After some time, dialog "Next Step" comes up reading that the Eris is "Unable to find HTC Sync on [my] PC...". I select "OK"
3) Now a "safely remove hardward icon" appears in the system tray of my computer and I'm able to do all the file transferring I want, close, safely remove hardware, and start again.

ANOTHER PIECE OF INFO:
What "USED" to happen works perfectly find on my roommate's Vista32 machine indicating that there's maybe something funny happening on the PC side of my Eris-PC debacle.