C:\DOCUME~1\USER~1\LOCALS~1\Temp\WER8bd7.dir00\appcompat.txt

Above error pop ups when Error Reporting is enabled on your system and w3wp.exe faces an error.
Windows Error Reporting increases Hard Disk space , by adding above pop ups in two different dump files i.e. HDMP and MDMP
HDMP (Heap Dump) – Uncompressed error dump file generated by Windows when a program has an error or crashes.
MDMP (Mini Dump) – Compressed Heap Dump files are saved as Mini dump (MDMP) files and may be sent to Microsoft as part of an error reporting process.

Windows Error Reporting settings are stored in Windows Registry at HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\Windows Error Reporting

However, if you do not choose to send files to Microsoft. These dump files will gradually go on clogging up your system disk space.
To avoid this you have to fix error in application and delete dump files present at
C:\WINDOWS\pchealth\ERRORREP\UserDumps

Read further for Customizing or disabling Windows Error Reportin.

Windows Error Reporting can be kept disabled or can be customize as per requirement.

On your Windows System >>> Right Click on My Computer >>> Click on Properties >>> Click on Advanced >>> Click on Error Reporting >>> You can Enable or Disable Error Reporting from here >> if you click on Enable >>> Click on Choose Programs for customizing.

To add w3wp.exe in exception list without Disabling Error Reporting navigate yourself as shown below : -

On your Windows System >>> Right click on My Computer >>> Click on Properties >>> Click on Advanced >>> Performance >>> Click on Settings >>> Click on Data
Execution Prevention >>> Turn on DEP for all programs and
services except those I select >>> Add w3wp.exe process in exception list
(Reboot not required)