At this moment I have 215 active and only one of this members get this message when she wanne post.
The page cannot be displayed
She can read every page, switch between every page only post is impossible.
Sometimes she can post a message (2) but the most time she get this error.
Can anybody give me some advice??
Sounds like your server isn't doing too well. Contact your host.
It could be several problems, but definitely not MyBB's. Her DNS could be messed up, or she could have problems with caching or she could be behind a firewall that blocks that page.
Either way, contact your host for further help as there isn't something I can do.
Could this help
I remember I had this problem with online banking once.
So I was looking in the faq from my bank
They say I must do this:
I hope I translate it in English well
start Internet Explorer
choose extra/tools
choose internet options,
choose tab general
click button delete files and click OK
click button settings
Check for newer versions of stored pages is on automatically, when not change it
change amount of disk space to use op 15MB and click ok
choose tab security
click button custom level
put security to medium and click on button and click reset
choose tab advanced
clcik on button restore defaults
click on button apply and OK
close Internet Explorer and restart internet exploder