I recently switched from Ubuntu through Wubi (Windows application) to a full Ubuntu OS. I am able to view streaming media like news/music vids etc, but when I try to play my own music/videos which are on my laptop the player's interface appears for a few seconds and disappears. I have tried with nearly every media player available and the same thing happens. Could anyone help please?

What app are you using to play your music? Is your music in mp3 format?
You may need to (re)install libxine1-ffmpeg
cheers,
jdk

Sounds like you are missing a lot of codecs. Install ubuntu-restricted-extras and the various gstreamer plug-ins.
Alternatively, you may need to check your configuration. How exactly are you trying to play those media? Streaming? Mounting your laptop drive using samba or NFS? Something else?

While I'm a bit of a linux newb myself, I was able to get all kinds of audio and video working on my recently installed distro of Unbuntu 9.04 on an ancient old PC hand-me-down.

What are the specs on your PC?

I'm assuming you performed the correct installation for your media playback software. If not, more on that below.

I also experienced a weird black screen when attempting to playback certain video (streaming or otherwise). I attributed it mainly to the fact that I'm only running a P4 2.2GHz with 512MB RAM (384MB for the OS and apps, and 128MB stolen by the woefully inadequate integrated vid card, me thinks)

At the black video screen I experienced, I just had to wait a while (in some cases a long while) - then the video finally appeared. Good ol' grandpa Dell 2400 coughed and wheezed and did his best to grunt out some divx movies, YouTube, etc. but he did finally do it. - I just may track down some used ram and possibly an old PCI vid card for gramps after all...

Anyway, I like the whole "go to the Synaptic Package Manager" trick in Unbuntu 9.04 to install codecs and the like. Did you do that? I had the best luck with VLC. (I've always liked VLC on my Mac and PCs so it was my first grab in terms of media playback software in this alien world of Linux)

Hope you get it working and enjoy using Linux. I know I am.

G'day. Synchro.
What you say sounds good. Although found that in Ubuntu, if I let it get all the codecs it fancied then 'Rythmbox' suits me for simple listening.
And yes jrjone. I too am finding Ubuntu to be terrific. Whenever I feel like throwing my computer out of the window, I make myself think back to how long it took me to learn to use win95 and apple running of of a 5.25" floppy disk.
So, like Synchro said. "Have Fun In Ubuntu"