Hi @abdul605 ,
Do you mean that the issue would show up when you click an item within your Gallery to navigate to Edit form?
Have you taken a try with different browsers to run your app?
Based on the issue that you mentioned, I have made a test on my side, and don't have the issue that you mentioned. Based on the issue that you mentioned, it seems that there is no enough available RAM to run your canvas app in your PC.
Please consider close some backend process in your PC, then try your app again, check if the issue is solved. Also please consider clear cache of your browser, then sign in PowerApps again, try your app again, check if the issue still exists.
You coul also consider re-start your PC, then run your app again in your browser again, check if the issue is fixed. If the issue still exists, please consider capture the App Id of your app, then submit an assisted support ticket for further help through the following link:
http://powerapps.microsoft.com/en-us/support/pro
Best regards,