video losing sync

[ebola]

Hello

I'm posting after a few weeks of research on the web without any result (actually I don't even know if that issue have a name).

I have some videos *.mp4 (maybe some other AVC containers) that are losing sync when played. Mostly in action scene or scenes with much movements. Then the video speed up a few seconds to get the sync back.
If I play/pause I can get the sync back or if I go a few seconds backward.
I tryed the same scene in WMP and SMP and it doesn't seems to lose sync in WMP. "Then use WPM" you'll say, but I don't like it, I like SMP ;p
I recently updated my FFDshow codec pack
My GPU drivers and windows are updated

My HTPC config:
MB = M4A88TD-V EVO/USB3
CPU = Athlon II x3 450
RAM = 2x G.Skill NT series 2GB DDR3-1333GHz Dual-channeled
GPU = Sapphire Radeon HD 6450 1GB GDDR3 fanless
SSD = Vertex 2 60GB
HDD2 = 2TB
COOLER = Noctua NH-U9B SE2
MONITOR = hdmi to Sony STH-DH520 (A/V Reciver) to hdmi to Philips 40PFL6606H/12
OS = Windows 7 x64

Thank you for helping me and please appologise any english mistakes I'm not english-speaking.

[rvm]

Try to change the cache setting, increase it or maybe set to 0 (sometimes that helps to improve performance on mp4 files).

[ebola]

Thank you for your answer

Cache for local files was set at 1000kB, I tried to set it at 4000kB ad 0kB as you've suggested but it hasn't changed anything.

[rvm]

See if changing the "correct pts" option in preferences -> advanced makes any difference.

Or upload a small video where we can see the problem.

[ebola]

No, it's not better (cache is set back to 1000kB)
I have no camera so it would be difficult to film my screen to show you.
Actualy it looks like the video and the sound aren't read at the same speed so the video comes later and later after the sound (up to ~3sec unsync) and when the video gets, I think, easier to be calculated it speeds up to catch the sound and get the sync back. It really speeds up, I mean maybe 2x normal speed.
Maybe I selected the wrong Output Driver, I already solved some issues by changing it, for now it's on "gl (fast - ATI card)"

My reference video is

Eagle eye (D.J. Caruso).mp4 (scene in the bagage terminal from 01.13.00,00 when the mains characters run the strairs up to 01.15.35,00 when they enter the plane, the sync is back - the gun shots are good (un-)sync points)
General
File E:/Vidéos/Films/Eagle eye (D.J. Caruso).mp4
Size 1731170 KB (1690 MB)
Length 01:57:35
Demuxer lavfpref

Video
Resolution 1280 x 528
Aspect ratio 2.42424
Format H264
Bitrate 1750 kbps
Frames per second 23.976
Selected codec ffh264

Initial Audio Stream
Format MP4A
Bitrate 255 kbps
Rate 48000 Hz
Channels 6
Selected codec ffaac

[davehu]

Set the cache to ZERO? now that's intuitive. after trying a dozen different settings, Zero worked. go figure.