Mac Mini slows down without any obvious reason
I have a problem where I can't find any reason..

At home I have a MacBook 13" with an 2 GHz Intel Core 2 Duo and 2 GB 1067 MHz DDR3 and
a MacMini 2,26 GHz Intel Core 2 Duo and 2 GB 1067 MHz DDR3. They are connected over a n-WLAN. On my MacMini I have several HD-Movies (mkv) which I want to watch on my MacBook. I use the Finder and the afp protocol to connect to my MacMini and start the movies with the VLC player (tried Plex too). Most of time there is no problem. The movies are played without any lags. 
But some days the movie hangs and I have no chance to watch it normally. When I connect to the MacMini via Screensharing there are performance problems too. I takes a lot of time before I receive feedback for my entered data. 

I checked the client (MacBook) and server (MacMini) network traffic but there are no noticeable problems. If I connect to a website from my client it builds the page as fast as usual. So I don't think it's an network problem.

One time I saw that the available memory on the server was just 10MB of 2GB. But another day it was about 500MB. 

The free hard disk space of the server is about 23GB.
The cpu is just about 3%

I rebooted the server but there was no improvement. 

I know I didn't provide much informations but perhaps you can give me some hints what to check next?

Ben
Mac Mini slows down without any obvious reason
===

I have a problem where I can't find any reason..

At home I have a MacBook 13" with an 2 GHz Intel Core 2 Duo and 2 GB 1067 MHz DDR3 and
a MacMini 2,26 GHz Intel Core 2 Duo and 2 GB 1067 MHz DDR3. They are connected over a n-WLAN. On my MacMini I have several HD-Movies (mkv) which I want to watch on my MacBook. I use the Finder and the afp protocol to connect to my MacMini and start the movies with the VLC player (tried Plex too). Most of time there is no problem. The movies are played without any lags. 
But some days the movie hangs and I have no chance to watch it normally. When I connect to the MacMini via Screensharing there are performance problems too. I takes a lot of time before I receive feedback for my entered data. 

I checked the client (MacBook) and server (MacMini) network traffic but there are no noticeable problems. If I connect to a website from my client it builds the page as fast as usual. So I don't think it's an network problem.

One time I saw that the available memory on the server was just 10MB of 2GB. But another day it was about 500MB. 

The free hard disk space of the server is about 23GB.
The cpu is just about 3%

I rebooted the server but there was no improvement. 

I know I didn't provide much informations but perhaps you can give me some hints what to check next?

Ben