Server Admin Graphs

I'm not sure if this is the correct thread to post this issue in, but maybe someone out there could help me out. My graphs for overall CPU usage and Network Throughput in Server Admin have stopped functioning properly. The other night they started showing flat CPU performance at 75% and network performance at about 250 bytes/sec. Other tools (iStat Menus and iStat Server connected to my iPhone) showed correct information. Today however, the graphs have stopped showing any data at all. They both say "There is no data in the selected period". I noticed the odd behavior when my VPN stopped working intermittently. Any suggestions?