Quicktime with a question mark

I am trying to play some Mp4 movies that I uploaded to my MobileMe gallery and I cannot play the same on my Mac. I get a question mark within the Q symbol. No movies on my MobileMe is playing after upgrading to 10.6. Any suggestions?

 

Thanks for the suggestion. I called Apple this am hoping to get a fix for this issue. Here is a summary of the conversation. Hope this helps y'all.

1) Updating to QT7 thru the SL disk didnt work.

2) The movies from MobileMe plays fine on a PC, so its a Mac issue

3) The support agent tried on Mac's that were running SL and told me the same issue. (Assures me that it aint a corrupt install of SL)

4) Didnt have this issue when using Leopard

5) MP4 and other videos plays fine when opened thru QT7 or QTX

6) Issue escalated to a specialist

7) Narrowed down to a plugin not compatible with Snow Leopard. Insisted that I download that particular file to the HD and view it thru QTX or QT7

Also, installing Perian didnt help and I have the Quicktime Plugin installed.

The specialist mentioned that this might be an issue with SL and there might be an update to QT or Sl itself to fix this issue later sometime. I am seriously thinking of going back to Leopard thru backup. Hope this helps everyone.

Alex