I did't know what I did, but suddenly I noticed that my windows 7 task manager's font is changed to a smaller font. Then I noticed all button's text font is changed. I tried resetting the fonts, do sfc /checknow, and re-installed segoe ui font, to no avail.
This registry update will help.
B) Save the .reg file to the desktop.
C) Right click the downloaded .reg file, and click on Merge.
D) Click on Run, Yes (UAC), Yes, and OK when prompted.
E) Continue on to step 3.
The source of the reg file (if you needed to create it yourself, copy the code into notepad and call it fonts.reg)