Hello World!
I contacted the webhosting company, they replied on Sunday evening after nine pm. I like how they have customer support all week through. So, does it work now with some valid html tags. And a single < ?

EDIT: OK, now it works perfectly! So, after all, it was because of the webhosting company having automated security measures. They replied that older versions of drupal used to have a security vulnerability, and they had a rule to tackle that problem. But since the vulnerability is fixed in the drupal version I'm using, they just disabled the security rule on our site. The company is Hostingpalvelu.fi and I like them =)