You didn't mention exactly when the Safe Mode lockup occurred so....please try using System Restore from a command prompt like this:
Try restarting the computer, immediately start pressing the F8 key, once per second till a select screen loads. Use the up/down keys to select "Safe Mode with Command Prompt" and press the "Enter" key.
The next step may require you to be quick. Log in as your normal username, and when the command prompt window loads, immediately type: "C:\windows\system32\restore\rstrui.exe", then press the "Enter" key.. When the System Restore window shows up, select a date prior to when the problem happened, click "Next", then follow the prompts to restart the computer and restore back to a time.
It might take you back to a time when things worked. If not, then you may have malware on the machine.. And even if the computer is restored and starts working again, please try scanning the computer with malware removal tools such as Malwarebytes, SuperAntispyware, or Hitman Pro. There may be an underlying infection that's causing the problem.
Hope this helps.
Grif