Sounds like it could be 1 of 2 things
1) spyware/rootkit even having a good av is not enough these days rootkits hide malware from av the only real way to check is to use a boot cd like kaspersky rescue cd
then run malwarebytes.
2) bad sectors or bad drivers try updating all of your drivers DriverMax
check your hard drive using hddscan
You don't need a powerful cpu to play 1080p video most video streamers use an atom or sigma cpu.
boxee box- 1.2 GHz Intel Atom CPU with a PowerVR SGX535 Integrated graphics processor.
WD Live TV 2 -Sigma SMP8655 Secure Media Processor.
If your watching 1080p best to use XBMC
, or boxee
i prefer boxee because its very easy to use but XBMC has more support.
If you use boxee or xbmc look up app repositories and look at navi-x.
I have a boxee box
it plays 1080p and takes load off my computer and allows me to stream 1080p movies from my pc to tv.
You will need codecs if you use any of the media center software so make sure you download ffdshow