What does this mean and how can I fix it?

"Could not initialize the browser's security component.
The most likely cause is problems with files in your browser's
profile directory. Please check that this directory has no read/write restrictions and your hard disk is not full
or close to full. It is recommended that you exit the browser and fix the problem. If you continue tou use this browser session,
you might see incorrect browser behaviour when accessing security features."

I get this alert when using PortableFirefox. I am also having problems downloading upgrades such as Flash player, recieving this message.

"C:\docume~1\user\LOCALS~1\Temp\r9cy46pp.exe could not be saved, because the source file could not be read.
Try again later, or contact the server administrator."

What am I doing wrong and how can I fix these problems? Thanks