I am about to decide which Linux to use during the next year and I have given a try to different Linuxes, and I am able to compare and say this only happened in elementary OS with exactly the same hardware.
When a video is displayed on an external monitor connected by VGA, once a few minutes the image freezes for 4-5 seconds (the sound is played normally).
The same video is displayed fine on the internal monitor of the laptop.
I have installed as many video codecs as possible, to no avail.
00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09) (prog-if 00 [VGA controller]) Subsystem: Sony Corporation 2nd Generation Core Processor Family Integrated Graphics Controller Flags: bus master, fast devsel, latency 0, IRQ 32 Memory at c0000000 (64-bit, non-prefetchable) [size=4M] Memory at b0000000 (64-bit, prefetchable) [size=256M] I/O ports at 8000 [size=64] [virtual] Expansion ROM at 000c0000 [disabled] [size=128K] Capabilities: <access denied> Kernel driver in use: i915 Kernel modules: i915 01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Seymour [Radeon HD 6400M/7400M Series] (rev ff) (prog-if ff) !!! Unknown header type 7f Kernel driver in use: radeon Kernel modules: radeon