Hammer stops working when I try to type the name of the map

[dmlxo21]

[IMG]http://imageshack.us/a/img203/7195/52838620.jpg[/IMG]
[IMG]http://imageshack.us/a/img515/3171/24788749.jpg[/IMG]

Actually, not only whenever I open a window(like open/save/save as.. whatever that you can load or save and type the name of them), it stops working.
I mean,
1. Turn on the hammer
2. Click Open or Save
3. Damn stopped working

I can't figure it out. I've forgot about it for months, however I just tried to touch it again then it reminds me this was why I stopped working on hammer.
Any idea please?