Reasons for Oops! Firefox could not find http
Some of the reasons I found in various discussion forums and troubleshooting articles are:
1. Lower Memory and high number of Tabs opened
2. Malicious Program ( I read it as Google Virus )
3. May be DNS resolving issues
4. Security Programs stop Firefox from accessing website details
This issue mostly happen when multiple tabs are opened in your computer. Then if we try to open a new Firefox tab, it may prevent (low memory) Firefox from loading the details of the new webpage. So Firefox shows this error message instead of displaying the link. Another possibility I read is the presence of some malicious programs which affect major browsers like Firefox, IE etc. This programs stop Firefox from displaying websites and redirect firefox to Google Search with a notice Firefox could not find the website.
If the firewall installed in your computer block Firefox from accessing website details, it can cause this issue. Last possible reason is DNS failure. If your computer failed to resolve the DNS queries, Firefox couldn't find the web page. So DNS issue is also a possible reason.
Solution to Oops! Firefox could not find http
Possible steps to fix this issue are:
1. Close unwanted Firefox tabs
2. Make sure Firefox is white listed in Firewall settings
3. Assign Open DNS or Google DNS to your computer
To get more details about assigning Open DNS in your computer follow the links below.
How to assign Open DNS in Ubuntu Linux PC
Assign Google public DNS in your computer
4. It is better perform a full system virus scan