Small window flashing open Windows 8.1 - Microsoft Community

using windows 8.1 , in last 2 weeks small rectangular black window appears , briefly trying open cannot.   reminds me of old dos window.   use windows defender , recent scan removed trojan reports no other issues.   use firefox.   not seem cause problems , working fine new concerned causing problems in background.   ideas.

hi marian,

for assist better, need ask few questions:

• were there changes made before experiencing issue?
• can send screenshot of rectangular box appears?
  
• what application or program using when box appears?
• what other troubleshooting steps have tried far?
  

looking forward reply can find best solution you.

thank you.

Windows / Windows 8.1 / Performance & system failures