At Ease is software from Apple which is fairly popular. For lab situations, you may prefer the workgroup version . In addition, Claris Corporation is marketing the Network Administrator Toolkit which will work with At Ease for Workgroups 4.0. On Guard , from Power On Software is another popular product. They also have some network configurations available, along with some network management software.
Free trials are available from their home page.
FoolProof from SmartStuff is yet another popular choice. They also have a Windows version of FoolProof software if you desire cross-platform support. With a CD, you can go to the startup disk control panel and change it to the CD or just hold down the C key as the computer starts up. Sometimes, but not often, this is caused by some bad extension somewhere. If that does not work, it is likely a hardware problem.