could be problems in my net connection (wifi, etc.)?
That's what the logic suggests. I sent a PM to myself (to Maraviollantes account) with that test account, and it worked quite fine. Could be also related to your firewall/proxy/Tor if you have something like that (I remember a while ago somebody else was using web proxy to access this forum, and they couldn't send PMs because of that).
Nope, I haven't used proxy, nor have I changed any system/security settings myself. And the curious thing is that I can send PM to Rose. Another curious thing is that during that last time I've such problem, I couldn't email him (who, incidentally, was also an admin) either - it just hanged up!
The deletion of my internet temp files doesn't help at all, so what I can do now is to hope that the problem would disappear itself in due course, like the last time, tho it didn't take this long back then. *sigh*[EDIT]
In any case, thx for your help, & Rose's, too.