X97M/Manalo is an Excel macro virus.
Based on the settings of your F-Secure security product, it will either move the file to the quarantine where it cannot spread or cause harm, or remove it.
A False Positive is when a file is incorrectly detected as harmful, usually because its code or behavior resembles known harmful programs. A False Positive will usually be fixed in a subsequent database update without any action needed on your part. If you wish, you may also:
Check for the latest database updates
First check if your F-Secure security program is using the latest detection database updates, then try scanning the file again.
Submit a sample
After checking, if you still believe the file is incorrectly detected, you can submit a sample of it for re-analysis.
NOTE If the file was moved to quarantine, you need to collect the file from quarantine before you can submit it.
Exclude a file from further scanning
If you are certain that the file is safe and want to continue using it, you can exclude it from further scanning by the F-Secure security product.
Note You need administrative rights to change the settings.
When an infected workbook is opened, X97M/Manalo.A checks if file "MANALO.XLS" exists in the Excel's startup directory. If the file does not exist, the virus creates a new workbook, infects it and saves it to there.
At October 3rd, 1999 and every day after that the virus activates its payload. At this time it shows a hidden sheet with some text and a flag.
X97M/Manalo.D is a modified variant of X97M/Manalo.A. It creates a workbook, "C B I.XLS", to Excel's statup directory.
This variant activates its payload at September 27th, 1999 and every day after that when it attempts to show an hidden sheet.