It is probably a port conflict (as a semi-educated guess). When I contacted MJ chat originally, they had me move the two MJ drives that you see along with the disk drives in My Computer to different drive letters.
Here is the transcript:
Steph: Plug in your magicJack. Now right click on my computer and select "manage". In there click on "Disk Management
JimF: OK, I am there.
Steph: On the right side you should among other things see two drives. One is called "MagicJack" and the other is called either "Phone" or "Vista Only". First right click on the one called "MagicJack" and then select "Change Drive Letters and Paths". In there select "Change" and then use the scrolldown menu to select "X". Click ok, you will get a pop up asking you to confirm, press yes.
JimF: OK, MJ is now drive X:
Steph: Now do the same thing with the drive called "phone" or "Vista Only". Name that one "Y
JimF: OK, Phone is now drive Y:
Steph: Now exit device manager and then unplug your magicJack. Now restart your computer and when you are up and running again, plug in your magicJack.
Note: this assumes that you see the drive icons at all. If they are not there, better check with MJ for more help. Also, I have found that when troubleshooting similar problems on my flash drive reader, it is best to set the BIOS in the motherboard to use "Plug And Play O/S" (as it is called for my Asus P5Q Pro). Otherwise, you can get drive conflicts without knowing it.
Of course, it could be something else, but I would give this a try.