URL in explorer shortcut?

Sounds like you recently changed your search engines or someone else did. The feature you mention is a standard feature in Firefox and IE for that matter. Basically anything put in the address bar that isn't a direct URL will call on the search engine to find the website. Check your search engines and make sure you have google or another decent search engine available.

Update: Try this then. Open a new tab. In the address bar enter about:config. Click on the promise to be a good boy and it will open a page of advanced settings. In the Filter: field, enter "keyword" without the quotes. This should bring up two or more settings. Double click the keyword.url field and in the "Enter string now" dialog replace whatever is there with http://www.google.com/search?btnI=745&q= as the URL. If the keyword.enable setting says false, double click it to change it to true. If it says, true, leave it alone. This will re-enable the address bar search using Google's I'm feeling lucky feature to take you to the top result from the Google search.