Welcome mkiz,
the third question is the most easy one to answer: Please access your Forum Profile (it's the third button in the second navigation bar above), select the Community tab and set the Content Editor to "Enhanced".
For answering the other two questions properly I would need at least some basic information about the system you're testing on. The "white blank space" is most likely due to a problem with your video card. "Can't seem to load the string quartet" could have quiet a few reasons, starting with missing instruments, installation problems and/or system performance issues.
The System Specifications shown on the MIR SE page of our site should give you an idea of what to expect from your system performance-wise:
-> [URL] http://www.vsl.co.at/en/211/497/1687/1913/1915/1555.htm[/URL]
Kind regards,
/Dietz - Vienna Symphonic Library