This is caused by the config file having a non-integer value (decimals) in the config file. The slider is under the PFTR buttons in the replayer. Adjusting the slider should return the config file value back to a whole integer. Deleting your config file to reset it to default should also solve this.
Please close HM2 and delete the holdemmanager.config and holdemmanager.bak files:
Windows hides 'known file extensions' by default.
Show Extensions :: Scott Granneman
Win7: C:\Users\username\AppData\Roaming\HoldemManager\
XP: c:\documents and settings\username\application data\HoldemManager\
Showing hidden files:
http://hm2faq.holdemmanager.com/ques...in+Windows%3F+
Please start HM2 and update to the latest build via HM2 > Settings > Check For Updates