said by Steam Forums :

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Missing or scrambled text in Steam menus
Question

My Steam application is missing text and/or the menus appear broken, how can it be fixed?
Answer
Windows system font

This problem may be due to a bad or missing Windows system font. The easiest solution is to install a known good font set.

Installing Missing or Damaged Fonts

1. Download the attached file by clicking the following link: SteamFonts.zip
2. Log out of Steam entirely, and close all other programs that might be trying to use these fonts
3. You might also have to temporarily disable "System Restore" for this to work:

Open Control Panel > System > System Restore > then check Turn off System Restore
4. After downloading the zip file use a zip utility such as winzip to unzip the file(s)

XP has a native unzip, just right-click on the zip and "explore" and drag and drop the files into a temporary directory
5. Open Control Panel and double click on Fonts
6. Choose File and then Install New Font
7. Finally, remember where you put the unzipped fonts and go to that directory
8. Select the font and choose 'OK'
9. The next time you start Steam you should be able to see all the text again

Re-install winui.gcf

The winui.gcf may periodically get corrupted. The main symptoms are missing text in Steam menus and the items in the My games, My media, and Tools tabs overlapping.

1. Exit Steam
2. Navigate to your Steamapps folder (default location: C:\Program Files\Steam\SteamApps)
3. Delete or rename the file winui.gcf
4. Launch Steam and test the issue

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