Windows explorer randon freeze on three computers on my Homegroup

three Win 7 home premium systems on homegroup are experiencing random Windows Explorer freezes multiple times daily. Is started four weeks ago and has gotten worse. I've run driver updates, run srf/ scannow with two of the PC's have errors have checked CBS log and the errors that are related to Windows failed updates (HRESULTS=0x800f080d CBS_E_Manafest invalid item 0x800f0805 CBS_E_ invalid Package. I've checked HHD are all good, have run three different vendors virus & malware scans on each which cam back negative. The only event I can think of is our power went out for two days just before these problems started but, only two computer related problem I encountered when the power came back on was access to our wireless connected Brother MFC9840CDW. I had to reconfig it to connect to FIOS router and each PC. And, one of the PC is part of Homegoup but doesn't always show up in Homegroup. The freeze is initiated by clicking an item on an open program on the desktop or taskbar. Even the system clock freezes. At this point I hesitant to upgrade to Win 10 without doing a clean install on all systems.
Any feed back is appreciated.

Thanks,
RichC

Thanks for responding.The power outage was caused by electrical storm however, all the PC plus the printer are on surge protectors none of which was compromised.

The spec's for one of the two Dell GX620 are listed in my profile (they are identical with the exception of the power supplies which failed early in their life. The 620's are experiencing more frequent freezes than the Dell Inspriron537. Yesterday, I resurrected a Dell 8600 laptop running Win 7 Home Premium, joined it to homegroup just to see if it would begin experiencing the same problems but, so far it's fine. When the system"s freeze Windows Explorer becomes unresponsive if task manager is open the system continues to report process activities but, commands from the mouse rarley function. The mouse "may" intermittently be moved around the desktop but clicking a program icon or window doesn't execute a response except a spinning blue circle.

When a system frozen Pinging its IP address returns confirmation. I'm wondering if a windows update may have initially caused the problem which has gotten worse over the last few weeks. Unfortunately, the systems have been rebooted too many to run system restore.