I am having the same issue, with Windows 7, chrome 3.0.190, when I download an extension, it goes to the process and works fine, I close chrome and when it starts all is gone. The only possible issue that I can see is that I have chromium in the same machine.
If this is the case, I will gladly remove it.
Thank you
Mario

I moved your post here since it had nothing to do with cookies.

Try reading through here and see if it helps you at all: Google Chrome FAQ

And what extension are you trying to install?

yes it did, thank you

NP...that's what we're here for :-D

I'm having difficulties enabling extensions. I've done everything as noted in the instructions, but when I go to add " --enable-extensions" I get the error:

The name 'C:\Documents and Settings\Chris\Local Settings\Application Data\Google\Chrome\Application\chrome.exe --enable-extensions' specified in the Target box is not valid. Make sure the path and file name are correct.

Any help would be appreciated.

Since you are using XP, there is a space in the command path (application data). It needs parenthesis around the Path\to\chrome only, to ignore the space. Use the following:

"C:\Documents and Settings\Chris\Local Settings\Application Data\Google\Chrome\Application\chrome.exe" --enable-extensions

thanks! works like a charm now

No problem, glad to see it working.