Nokia 5800 problem

hi guys, help me out please.

Basically my problem is videos i have on my Nokia 5800 phone, when i transfer them from my PC they appear on my phone, no problem, but then after a while give about a couple of hours, it disappears(I mean like i cant find it using my phone) but when i check the contents of my phone using my PC, its still there. This has happened alot help please, thanks in advance

by any chance the phone does not recognise the video format???

I also used a nokia 5800, and sometimes it happens. Just download an F explore, browse and open the video from it. it works

its working fine now, but it happened before.

As in i was watching it then. then when i turned my phone off it went invisible from my phone

i changed the program i use to put videos on my phone s its all good now