Steam thinks I'm not connected
 

For some reason, Steam has suddenly started displaying the following message when I try lo launch CoD:

'steam.exe (main exception): To run Steam you must first connect to the internet'

I am very definitely connected to the internet and have been playing CoD for over a year without this problem occurring.

I'd be grateful for any suggestions as to what is happening and what the solution is.

Just an update - I ran the 'Install Steam' program again (without uninstalling the existing program first) and all seems to be back to normal. Presumably the original installation had become corrupted somehow.