Some PC and networking questions

1. Workers can not print from the printer, there user log on are correct and are allowed to print from that printer in active directory. How would you resolve this issue?
2. What is the difference between hub and switch?
3. Your hard drive is partitioned as follows: 8 gigs for OS drive C, 8 gigs for Hot Swappable dirve D and rest is free as dirve E. Your drive C crashes, how would you reboot your system without installing a new operating system?
4. Your computer gives you “non-disk error” before you log on what would you do to make your computer work?