Help WIFI odd disconnects (not same problem as the big post)

[KelDG]

Hi all, I am having problems with the WIFI on my Samsung galaxy Mini.

**(This is not the same problem as the other big post on this page, I have read it start to end. I have also searched the forum for similar problems but no luck)**

If I tell the WIFI to never sleep, the connection is solid and never drops.

However if I have it on the default "WIFI sleep when screen turns off" (for better battery life) then randomly when I bring the phone out of sleep to use it, the WIFI does not reconnect.
(The WIFI at this stage is not "scanning" or trying to reconnect it is simply "disconnected")

It reconnects fine some of the time but other times it will not have the WIFI reception bar and there will be no internet access through my router. I have to manually turn the WIFI off and on again for it to re-establish a connection. **

Any ideas why this might be happening?

I have tried this on 2 different routers with the same results
3G is completely disabled
Phone is completely stock, and I have tried a factory reset.
Model number : GT-S5570
Android version : 2.3.5


Thanks

Kel