Cisco VPN

My wife works from home, connecting to her work through a Cisco VPN. She can connect with no trouble but is kicked off after 5 to 8 minutes even if she is actively sending and recieving e-mails or other files. She can still access the internet while off VPN. I often work from home too though the basic Windows VPN and never have problems. I can be on while she is off. We have cable internet and a Linksys router. Any suggestions?