我部機唔知點解最近行得好窒，播歌、睇戲、打機都窒下窒下

d聲都窒下窒下，好似播緊 remixed 甘， 一個音窒—兩秒

點解會甘架?????

我試過重組hd ，但都唔得

may be you got either virus or spyware from internet.  Those programs are running at the background, it will take up a lot of your system memory.  You better update all your anti-virus or anti-spyware program and scan your system completely.

You may repair or re-install your OS. Playing games or videos would perform a lot of read/write on your harddisk.  Sometimes it might crush your drivers, hence it causes instabilities.  Also, you must free up as much HD space as you can for these tasks.  If you have only 20% left in your HD and your files are scattered around, it will take much longer to process.  This may be the reason.

有無試cleanup spyware? 行一次scan virus後, 再scan spyware, 然後再cleanup registry, 咁應該會有幫助!

Maybe your hard disk is going out.
Depending on the brand of your hdd, you may use their utility to check the health of the hdd.
E.G. Seagate has seatools desktop, Maxtor has PowerMax, etc...you can download them at their website.