Work for a Few Days for Some Errors

I set up the first VM as of Ubuntu 10.04-i386 with 8GB storage. And then went into the stage of installing it, however another problem appeared that no display in the window of virt-manager only with the message that "Graphics not active for the guest vitual system". Well, it was the time to figure out new things again. As I checked over all settings again, nothing need to be changed to fix the issue. Then I tried to restart the computer, and cleaned up all cache files by typing:
sudo apt-cache clean
I suddenly thought about that the virt-manager may require the root permit for running the VM, so I tried again with typing:
sudo virt-manager
The problem changed as there is display in the controller which I want, however new errors came out and displayed in the console which are gtk errors and those errors are about a package called "pixmap". I searched the software centre that the package was a theme package which only has something to do with the display. Sooo, I then set this issue aside and got my VM to run.

As, I set 512MB memory and 2 cores to the VM, the procedure of installation was actually quite long, about one hour and 20 minutes.
Maybe, I should to assign more memory to it for better performance.
Consequently, I shut down the VM and restarted the VM, new errors came out:
libvirtError: cannot connect to 'localhost:8000': rejected
Wow, this is very interesting, I thought I fixed all the connection issue prior to the beginning of getting VM started. I thought that I might find something in the configuration file of Xend, I typed:
sudo gedit /etc/xen/xend-config.sxp
And just as my expectation, after I looked over the file, I found that:
#(xend-port            8000)
With the # in the first place, this port is not active; by removing the # mark, it should be OK. I did remove it, and restarted VM, and it worked!!!

I went into the VM(I call it u10) with only first ten minutes happy, cause very soon found new problems:
1. The display is only with the resoluation 640*480
Nothing can be changed in the system setting
2. The Vm is working in a very slow speed which is esaily recognized.
When moving mouse, it delayed and is really lagging.
3  No network nonnection
The vitual networking card is always checking and trying to connect a network which does not exist.