|The bios normally selects boot order based on what someone (maybe you/maybe cpu company) told it the order should be. Either the order has changed as above. The system is trying to boot (it seems) solely to the Network Interface Card. |
The second reason is bios can not find a bootable media that is higher up in selection choice list.
Start at bios to view boot order.
"Best Practices", Event viewer, host file, perfmon, antivirus, anti-spyware, Live CD's, backups, are in my top 10