Ok, so I downloaded and installed the Zbrush trial version onto my computer. Earlier today, while installing a program my computer seriously messed up so I had to restore it using a system restore point a couple of days ago. Unfortunatly, after doing this, I cannot load Zbrush because it tells me there is a problem with my licence files. It gives a telephone number to get a key to use to access Zbrush again, but I cannot use this as it is only for people that have bought Zbrush and I am using the free trial.
I’m guessing there is no hope for me to be able to use it again without buying it (which really isn’t an option for me right now, I just wanted to practise using the software as much as possible in the time given.) but I thought I’d try posting here anyway to see if anyone has any info. It’s annoying because I have other trials running on my computer which are still working despite the restore, and I still had 16 days left. 
Any help is much appreciated.
