Functionality on XP64 Pro versus Windows 7?

[frank_anomaly]

I've been running Splash Lite on a machine that has an Athlon 64 3700+ (single core) CPU and an nVidia Geforce 210 graphics card. I've been going back and forth between booting from a Windows XP64 Professional (with all applicable updates) system drive and another that has Windows 7 Release Candidate.

Running under XP64 Pro, with Splash Lite 1.0.5, and now 1.1, I'm getting what appears to be "slow motion" (smooth, but very slow, like a sports instant replay) playback in an H.264/AVC 1280X720 mkv file with the hardware acceleration option enabled. If I try to run the file without the hardware acceleration, the video is faster, but way out of sync with the video. I did a complete uninstall and reinstall of 1.1; same results. I updated to the latest nVidia driver; no change.

Under Windows 7, the same mkv file (playing off the same, non-system hard-drive) played perfectly in whichever pre-1.1 version of Splash Lite I had (probably 1.0.5, but it could be 1.0.4; don't you guys like "about . . ." screens?), and now in 1.1. With hardware acceleration enabled, CPU usage by Splash Lite is indicated to be in the low teens in the Task Manager; with it not enabled, CPU is 70-80, but the file still plays smoothly.

Is there something about XP64 Pro and a machine of these particular specs that you would expect would cause Splash Lite not to work properly, or is there something weird going on? (The machine, under XP64 Pro, ran earlier versions of Splash Lite properly, but I believe at that time I was still running an ATi Radeon graphics card.)

[Ghost]

Does the problem with slow mo video started after installing nVidia graphics card in the place of ati?
Does this slow mo effect repeats for all H.264/AVC videos or only for specific mkv?

Btw, in next Splash Lite there will be information about version included in Settings window