Hmm! I'm not always a good Egyptian either. The key word here is DownLoading. This can be a problem in error correction of the modem or Windows setup causing the file to be corrupt. It can also be a problem in many peer to peer networks where the file has been made poorly or been floating around to long. Although Hash numbers are supposed to keep this from happening. It still happens.
Another issue is that all digital video is sync to audio. If the audio can not be controlled or there is to much drift in the clocks or the audio does not control the video well or the video is not accepting control (more rare these days) there will be problems ranging from simple jitter to full lock ups.
A good place to start is with a commercial DVD. Open Messages within VLC and play a DVD. The Messages should be quiet (no errors). Open your task Manager before playing a DVD and note the CPU usage. Then Play a DVD giving a few moments to allow the CPU usage to settle. There should be no difference in CPU usage from the stopped state to the running state. Then watch the DVD. The picture should be stable. If you feel there is a slight jitter, try shutting off the "Skip frames" option in Preferences, Video. Then press Save and close the player.
Assuming that you have gotten past these tests the way I have described we can go on. If you haven't, try updating your Audio and Video drivers. and try again. You should also be sure that the Optical drive has DMA turned on, if you continue to have problems here. It also doesn't hurt to update DirectX runtime. These updates are not automatic and the version will not change from 9c. (6/06)
Now comes the fun part
DownLoading files. I spent a fair number of days reading and examining my connection and every time I move some nice person is willing to help me get going with a new connection and always manages to screw it up. The issue these days is a secure connection at the best speed (up and down) possible. Unfortunately this could be a book on its own depending on the connection and hardware, plus how Windows recognizes this and what your IP provider requires. Plus there are some hidden cashes in Windows that can become corrupt.
Some help can be gained on line:
http://cable-dsl.home.att.net
http://www.dslreports.com
Once you have gotten by this there is still the possibility of getting files that are already corrupted and don't play properly for one reason or another. Sometime it's just bad encoding. I have found that the only defense is a second opinion. Another player capable of playing the format in that container.
Yet may people come to using VLC because of the number of formats it supports and or because Direct Show is screwed up and won't work for them and the majority of players out there are Direct Show based.
Now aren't you glad you asked?