March 29, 2011 12:24 PM PDT
Hi dani dani dani
you can use "Synaptic Package Manager" which is in the preferences menu. It maintains all software packages. Its not as intuitive as the software center, but is very easy to use, and if you know the name of what you are looking for, you can simply type it in the search window and it will find it for you.
I am not sure about flash as I have not seen the problem. I will look further into that if you can also post a little more about the hardware you are running on so we can understand if its a flash or video card type issue, etc...