VideoStudio :: X4 Hangs At Capture?

My capture card is a BlackGold BGT 3620 (which doesn't come with capture software). I had been using VideoStudio Pro X3 to capture VCRs through its analogue input (using S-Video) with no problems. However, I recently re-installed Windows (nothing different, it had just stopped working), and decided to give the trial version of VideoStudio Pro X4 a shot. When I go into the capture panel and click on "Capture Video", the "Source" field is blank, and the program completely hangs, so I have to kill it.

Of course, I can go back to X3, but sooner or later, it will no longer be supported, or there'll be some other reason I'm forced to upgrade, so I'd rather get this working.I tried running it as admin (although X3 used to work fine without it).

here's my set-up:

Mobo: ASUS M4A79T Deluxe
RAM: 8 GiB DDR3
GPU: Palit NVIDIA GeForce GTS 250 (driver V. 275.33)
HDD: 3 x 160 GB 7200 RPM SATA II
OS: Windows 7 Ultimate x64. All service packs, updates, etc., installed.
Capture Device: BlackGold BGT 3620 (driver V. 8.1.0.0)
Capture Media: UK PAL VCR, from standard VCR player, through S-Video