Galaxy W (Android 2.3.5) wlan problems

I have a Samsung Galaxy W phone on which I have problems connecting to ONE specific wifi network. The phone is running Android 2.3.5 (Gingerbread).

The wifi network in question is a shared connection on a Windows 7 64-bit computer. This worked nicely for a while, until I suddenly managed to select "forget network" on the phone by mistake. After that, the network never shows up on the phone (under the normal WiFi tab OR with any app that can find wifi networks).

Not even when I add the WiFi network manually does it work - then it just says "Not in range".

To be completely certain that the problem IS on the phone, I'm also connecting to the same shared network from my Galaxy Tab, running Android 4. This works perfectly - the network pops up at once.

So, to summarize: After telling the phone to forget the network, it can no longer see the network or connect to it manually.

Anyone got any suggestions? Or do I have to reset the whole phone?