I been using Garena Plus to play Heroes Of Newerth and same as you, I have also encountered a lot of weird garena problems. The most rare of this problem is
"You cannot login using you Garena Plus Messenger" like this photo.
I have attempted to find a solution about this since the Game moderators are kinda busy and I cannot really find helpful solution. Just follow these step I did when I encountered this proble.
[Windows Only]
1.) Go to control panel and go to network settings (Network and Sharing Center).
2.) Find and select "Change adapter settings" (You can see this in your left side of you screen).
3.) Find you approriate internet adapter like on the photo below.
4.) Right click the adapter and select "Properties", after you click it a popup windows will appear like in the photo below.
5.) Select the "Internet Protocol Version 4 (TCP/IPv4) and click "Properties" button or simple "double click" it and again another popup window will appear like in the photo below.
6.) Read carefully. Make sure you select the circle button (Radio button) which has label of "User the following DNS server addressess:". Once you do that the textbox below will be active.
7.) Now we will be using the Google public DNS Server address (Note: You may use other DNS Server if you know other). Now on the first textbox type 8.8.8.8 and on the second box type 8.8.4.4
8.) Lastly, save it. Just click the "OK" button or you may also validate the settings by ticking the checkbox labeled ("Validated settings upon exit").
There you go. I solve my login problems using the methods here. Guys if this happens to help you, better share this so other players will know and kindly drop comments if this helps you also. Happy gaming pals...