I'm assuming you are referring to importing the product file correct using the Products and Plugins feature in admincp? If so, can you try installing the product file of a simple plugin off of
vB.org and see if it exhibits the same issue?
The only reason I could think of that might cause something like this is that the web server was not being responsive but it should have killed the process after 90 seconds or so. The other option is that it would appear to be waiting but for some reason you had lost Internet connectivity on your end.
Let us know the outcome of installing a simple plugin.
Thanks
Mark