如图所示，Adobe Acrobat reader使用一段时间之后，打开一个pdf文档，鼠标指针在空白的地方很奇怪的变成了一个黑方块，非常影响阅读体验： 
Adobe 官网给出的解决方案：
Mouse pointer changes into a black box
If your mouse cursor changes into a black box when moved over blank areas in a PDF document, use the solution below as a workaround.
The problem is intermittent in nature, and reported for the May 2016 release of Acrobat Reader DC and Acrobat.
Solution: Remove the icon cache file
Adobe is working to resolve the issue. Meanwhile, follow these steps as a workaround:
1. Open the local appdata folder:
C:\Users\USER_NAME\AppData\Local\Adobe\Acrobat\DC
2. Delete the following file in the local appdata folder:
For Acrobat Reader DC: IconCacheRdr.dat
For Acrobat DC: IconCacheAcro.dat
3. Relaunch Acrobat Reader DC or Acrobat DC.
也即打开这个目录：
C:\Users\USER_NAME\AppData\Local\Adobe\Acrobat\DC
该目录下有 IconCacheRdr.dat文件，删除即可(以及文件名中 带“IconCache的.dat文件”)，然后重启Adobe Reader,鼠标指针变回正常状态：
