This error signifies that the IPAC board is being seen, but the OS can't connect to it. Unfortunately this is sometimes indicative of the IPAC nearing the end of its life.
However, a (potentially only temporary) way to fix the error is to:
1.) Disconnect the IPAC from its USB connections
2.) Start up the machine
3.) Reconnect the IPAC via USB.
This should let you start up the machine and play just fine, but if this fix ceases to work, then it's usually a sign that your IPAC board needs to be replaced.
You can find replacement IPACs HERE, or e-mail support@bumblebeargames.com if you suspect that your IPAC is dead.