If I had a customer on the phone first I would explain that my system crashed and that it may take some time to reboot. I would ask if the have the time to wait with me while it reboots or if they would prefer I call then back. Or if I have the ability to do transfer the customer to someone else I would also offer that as an option to them. If after system reboots and the problem still exists and the customer is still in the line with me I would then apologize and explain that I would not be able to help them right away and ask their preference fit me to call then back our if possible transfer to someone else our ask then to call a specific number to complete the business. After the customer was taken care of I would immediately take steps to correct my computer by calling in whatever help necessary.