Excel error, stops running macro - excel

Question

I am experiencing an odd bug on Excel. I have a macro that shows a non-modal userform when I press CTRL+m (Macro shortcut). Every once in a while, and it's not that frequent (Shows up once or twice during the day, I use the macro every 5 minutes or so), Excel won't run the macro, won't show the userform and will just beep (as in "mistake, cannot proceed executing code").
I went into the Macro window to try to press "Run" and manually execute, but all buttons are disabled, except for "Create". If you click it, it says the macro name is not valid. As you can see in the screenshot below, the name of the macro shows the instance where the code is (Sheet1 of the workbook).
Sometimes it can be fixed by saving the workbook and just re-trying, but sometimes it doesn't; when it doesn't, I run a different macro (by double clicking a specific column) that shows a modal userform, and executing its code. Then my first macro returns to normal.
Any help will be very much appreciated.
Edit: Adding the code as requested in the comments
Sub ShowCommentWindow()
Dim myCell As Range
Dim companyColumn As Long
Dim wbk as Workbook
Dim company as String
Dim phone as Long
Set wbk = ActiveWorkbook
For Each myCell In wbk.Worksheets(1).Range("A1:Q1")
If myCell.Text = "Company" Then
companyColumn = myCell.Column
company = ActiveCell.Text
phone = ActiveCell.Offset(0, 4).Value
Exit For
End If
Next myCell
If ActiveCell.Column = companyColumn Then
If EmailForm.Visible Then
GoTo ExitProc
Else
If Not ActiveCell.Row < 4 Then
ActiveWindow.ScrollRow = ActiveCell.Row - 3
Else
ActiveWindow.ScrollRow = ActiveCell.Row
End If
If CommentWindow.Visible Then
CommentWindow.AddButton.SetFocus
CommentWindow.CommentBox.SetFocus
Exit Sub
Else
CommentWindow.Show
ManageComments
AddComment
End If
End If
End If
ExitProc:
End Sub
Edit2: Posting more code, for QueryClose:
Private Sub UserForm_QueryClose(Cancel As Integer, CloseMode As Integer)
Dim myCell As Range
Dim isCompany As String
If Not CommentWindow.CommentBox.Text = CommentWindow.TextCopy.Text Then
saveConf = MsgBox("Changes have not been saved yet. Do you want to save?", vbExclamation + vbYesNoCancel + vbDefaultButton2, "Save changes?")
If saveConf = vbYes Then
Call SaveComment
GoTo ExitProc
ElseIf saveConf = vbCancel Then
changed = True
Cancel = 1
CommentWindow.AddButton.SetFocus
CommentWindow.CommentBox.SetFocus
'CommentWindow.CommentBox.Text = CommentWindow.TextCopy.Text
Else
CommentWindow.TextCopy.Text = CommentWindow.CommentBox.Text
GoTo ExitProc
End If
Else
If Not changed = True Then
GoTo ExitProc
End If
End If
ExitProc:
End Sub

Answer 1

Seems like the issue is not unloading the forms from ( Unload(UserForm) )
This leads to a memory leak.
Even the official documentation -this refers to Access, but, should behave the same for Excel (there's no Form object or userform documentation there)- state the Lifecycle is Unload->Deactivate->Close, and this should happen when you close the userform as well, daily usage has shown that Unload if not stated may not be triggered when closing the userform.
The lifecycle is not that strictly monitored sometimes, but, that may lead to memory leaks and strange behaviors, always when working with objects you shouldn't rely that garbage collector will clean them if not specified. Probably adding something to confirm that terminate is being correctly handled will be helpful.
EDIT
If you're having problems remembering the unload -or still having problems with memory-, it will be a good practice to do the following:
Sub MyMainProcess()
Dim myform As UserForm1: Set myform = UserForm1 'this is your UserForm name
myform.Show
'my stuff needed...
Unload myform
Set myform = Nothing
End Sub
Unload and Nothing to clean as much as possible with coding

Answer 2

I see that you're calling an "outside" macro (it's not within the active workbook) - Is it possible that then those roughly 2 times a day that it doesn't work that workbook (Database 2 Lumber.xlsm) is being used by someone else at that time (eight running that, or another macro?).
If so, What I have done before is save a local copy of the workbook each time the macro is run