I start using the new Teensy 4.1 and I downloaded the Teensyduino.
Since then I have only problems with the USB connections. Serial monitor drops out, and I get upload errors every other time.
Cant live like that, I upload about 100 times a day.

I was a user of the Teensy 3.5 and 3.6 for years. I was using it with Arduino interface and teensyloader 1.52.
That version will not offer me the 4.1 board.
Can I delete that version and use the new teensy loader 2.0 that comes with the new one?

I can't even find the 1.52 on the HDD.
What is the best thing to do?

Teensydoino gives me these kind of glitches
When it glitches I get:

java.lang.reflect.InvocationTargetException
at java.awt.EventQueue.invokeAndWait(EventQueue.java: 1349)
at java.awt.EventQueue.invokeAndWait(EventQueue.java: 1324)
at javax.swing.SwingUtilities.invokeAndWait(SwingUtil ities.java:1353)
at processing.app.inputPipeListener.update_gui(Teensy PipeMonitor.java:321)
at processing.app.inputPipeListener.run(TeensyPipeMon itor.java:284)
Caused by: java.lang.NullPointerException
at java.lang.String.<init>(String.java:198)
at processing.app.FifoDocument.processAppended(FifoDo cument.java:255)
at processing.app.inputPipeListener$1.run(TeensyPipeM onitor.java:313)
at java.awt.event.InvocationEvent.dispatch(Invocation Event.java:301)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.j ava:758)
at java.awt.EventQueue.access$500(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:709)
at java.awt.EventQueue$3.run(EventQueue.java:703)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessI mpl.doIntersectionPrivilege(ProtectionDomain.java: 74)
at java.awt.EventQueue.dispatchEvent(EventQueue.java: 728)
at java.awt.EventDispatchThread.pumpOneEventForFilter s(EventDispatchThread.java:205)
at java.awt.EventDispatchThread.pumpEventsForFilter(E ventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarch y(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispa tchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispa tchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThre ad.java:82)