apparently it is *usually* a legitimate file, however if it is found in-
c:\windows or c:\windows\system32 folder
-it is said that it is most likley disguised malware
i found a reference to the file suggesting it may be used in symantec software (link leads away from computerforums.org)
Error: 7026 "Boot start or system start driver failed to load . . . gernuwa" when launching a pcAnywhere 11.0 host
in any case, it is not a core file and deleting it shouldn't affect your computer adversly. although it may cause any related software to function incorrectly.
either way, i personally have never seen the file in my task manager, so scanning your computer might be a good call
and as far as *what* the file actually is- (link leads away from computerforums.org)
Gernuwa.sys Windows process - What is it?
GERNUWA.sys error - GERNUWA.sys error causes and how to fix it
oh and dont download any of the software they tell you to download, these pages just have some basic info on the file
hope that helps =)