Computers visible but not accessible

Hello

Setup

Linksys modem
Belkin pre N router
PC1 connected by cable to router
PC2 connected wirelessly to router with Belkin pre N wireless network
windows 2000 on both PCs

Internet works on both PCs through the router.
PC1 can see PC2 on the network but when trying to access it says 'The
network path was not found'
PC2 cannot see PC1 on the network
Folders are set for sharing and Network has been added under the security
tab

Also can receive e-mail through Outlook but cannot send. The mails seem to
go as if everything is OK but they never arrive at destination. Ive been
testing this by sending to my hotmail address but they never arrive

Any ideas on the above problems especially the first.

Ian