Hi, I am not fully sure this is a malware issue.,especially after an install. Did you Re format the drive first?
The file grep.exe is related to Yahoo! Widgets, formerly Konfabulator. have you just added this?
Do a file search and locate it's path(s).
Across all ThreatExpert reports, the file "grep.exe" has never been identified as a threat. ThreatExpert
You can also submit the file to any or all of these file scanning services. Please post back their reply to you in this topic.VirustotalJotti's malware scan ThreatExpert Submission Applet