I take it these are within the same /24 subnet? You've said there are no statics on the fileserver so that rules that out. Have you tried a tcpdump from the fileserver if it's a unix box?
Can you ping the fileserver from the .149 box?
From another machine on the same subnet, can you ping 192.168.7.149, and if you do an arp -a afterwards, does the mac address match up with the machine in question?
Normally this sort of problem is a dodgy arp entry on the gateway router but it sounds like you're on a flat network. Maybe duplicate IP, where the offending device doesn't respond to ICMP? Have a look at the router that holds the subnet's default gateway (if there is one) to see if the arp entry marries up?