Windows 7: Can't see LAN shared drives from wifi laptop, OK when on LAN

Hi everyone
First post here but wondering if anyone can shed some light.
I'm running a Windows7 Home Premium 32bit on a desktop and want to share its drives with the network. The desktop is LAN connected to the Wifi router and has no issues. If I LAN connect to the router with a laptop, I can access the desktop shared drives but I want to be able to access them via Wifi on a laptop. The Laptops have no problems accessing internet through wifi but will not see the shared drives on the LAN via Wifi and I have to plug in to the LAN.
I thought I'd cracked it as Kaspersky had the home wifi network down as public and I did have access via wifi for a short time, but it soon disappeared. I haven't removed Kaspersky yet to see if that helps. I've looked around via google and have tried numerous things and pinging seems to be inconsistent. Have tried rebooting router etc. Just wondering if anyone has had anything similar and a blindingly obvious solution/link.
Thanks in advance.

Hi

This sounds like a firewall issue, what happens if you turn it off completely? Personally, I recommend Microsoft Security Essentials (as do most people on the forum). If switching off the firewall resolves this problem, I would uninstall Kaspersky and install MSE.

Regards
UKMedia