Final answer:
The SFC command is likely to fix corrupted system files causing issues with starting an Internet browser by replacing them with correct versions.
Step-by-step explanation:
When Joe, a user, is unable to start an Internet browser, the most effective command to resolve potential file corruption that might be the cause of the issue is the System File Checker (SFC). The SFC command scans for and restores corrupted Windows system files. To run the SFC command, Joe should open the command prompt as an administrator and type in sfc /scannow, then press Enter. This process will scan all protected system files and replace incorrect versions with the correct Microsoft versions.